Helm's tag viewer does not allow the user to enter multiple tags.

1. Enter org mode
2. Type the following:
* test
3. C-c c-c where point is on * test
4. Type one tag in :a:
5. Expect :a: to the side of * test
6. C-c c-c at the same place
7. Type :a:b: RET
8. Expected: :a:b: Actual: :a:

Helm configuration:

(use-package helm
:ensure t
:demand t
:diminish helm-mode
:bind ("M-x" . helm-M-x)
:config
(helm-mode 1))

In GNU Emacs 26.3 (build 1, x86_64-apple-darwin19.5.0, NS appkit-1894.50 Version 10.15.5 (Build 19F101))
of 2020-06-27 built on jupiter.local
Windowing system distributor 'Apple', version 10.3.1894
Recent messages:
Loading /Users/robin/.emacs.d/project-management.el (source)...done
Loading /Users/robin/.emacs.d/shell.el (source)...done
Loading /Users/robin/.emacs.d/custom.el (source)...done
Turning on magit-auto-revert-mode...done
Starting Emacs daemon.
When done with this frame, type C-x 5 0
command-execute: Wrong type argument: commandp, projectile-command-map
Quit
helm: Error: Trying to run helm within a running helm session
delete-backward-char: Text is read-only

Configured using:
'configure --disable-dependency-tracking --disable-silent-rules
--enable-locallisppath=/usr/local/share/emacs/site-lisp
--infodir=/usr/local/Cellar/emacs-plus@26/26.3/share/info/emacs
--prefix=/usr/local/Cellar/emacs-plus@26/26.3 --with-xml2 --with-gnutls
--with-imagemagick --with-modules --with-rsvg --with-ns
--disable-ns-self-contained'

Configured features:
JPEG RSVG IMAGEMAGICK GLIB NOTIFY ACL GNUTLS LIBXML2 ZLIB
TOOLKIT_SCROLL_BARS NS MODULES THREADS LCMS2

Important settings:
value of $LANG: en_US.UTF-8
locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
projectile-mode: t
rainbow-delimiters-mode: t
doom-modeline-mode: t
helm-mode: t
helm--remap-mouse-mode: t
global-diff-hl-mode: t
evil-leader-mode: t
global-magit-file-mode: t
diff-auto-refine-mode: t
magit-auto-revert-mode: t
global-git-commit-mode: t
async-bytecomp-package-mode: t
global-undo-tree-mode: t
undo-tree-mode: t
shell-dirtrack-mode: t
evil-mode: t
evil-local-mode: t
global-whitespace-mode: t
show-paren-mode: t
mode-icons-mode: t
global-hl-line-mode: t
global-hl-todo-mode: t
hl-todo-mode: t
display-time-mode: t
global-linum-mode: t
global-company-mode: t
company-mode: t
override-global-mode: t
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
electric-indent-mode: t
mouse-wheel-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
column-number-mode: t
line-number-mode: t
auto-fill-function: do-auto-fill
transient-mark-mode: t
hs-minor-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug sendmail winner helm-command helm-elisp
helm-eval edebug helm-info ido projectile grep compile ibuf-ext ibuffer
ibuffer-loaddefs hideshow rainbow-delimiters elec-pair doom-modeline
doom-modeline-segments doom-modeline-env doom-modeline-core shrink-path
rx f s all-the-icons all-the-icons-faces data-material data-weathericons
data-octicons data-fileicons data-faicons data-alltheicons memoize
exec-path-from-shell helm-mode helm-files helm-buffers helm-occur
helm-tags helm-locate helm-grep helm-regexp helm-utils helm-help
helm-types helm helm-source eieio-compat helm-multi-match helm-lib
cus-edit cus-start cus-load wid-edit ox-twbs ox-odt rng-loc rng-uri
rng-parse rng-match rng-dt rng-util rng-pttrn nxml-parse nxml-ns
nxml-enc xmltok nxml-util ox-latex ox-icalendar ox-html table ox-ascii
ox-publish ox org-bullets org-element avl-tree generator org org-macro
org-footnote org-pcomplete org-list org-faces org-entities noutline
outline org-version ob-emacs-lisp ob ob-tangle org-src ob-ref ob-lob
ob-table ob-keys ob-exp ob-comint ob-core ob-eval org-compat org-macs
org-loaddefs find-func cal-menu calendar cal-loaddefs diff-hl vc-dir
ewoc vc vc-dispatcher evil-leader evil-magit magit-submodule
magit-obsolete magit-blame magit-stash magit-reflog magit-bisect
magit-push magit-pull magit-fetch magit-clone magit-remote magit-commit
magit-sequence magit-notes magit-worktree magit-tag magit-merge
magit-branch magit-reset magit-files magit-refs magit-status magit
magit-repos magit-apply magit-wip magit-log which-func imenu magit-diff
smerge-mode diff-mode magit-core magit-autorevert autorevert filenotify
magit-margin magit-transient magit-process magit-mode git-commit
transient magit-git magit-section magit-utils crm log-edit message rmc
puny dired dired-loaddefs format-spec rfc822 mml mml-sec epa derived epg
gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse
rfc2231 rfc2047 rfc2045 mm-util ietf-drums mail-prsvr mailabbrev
mail-utils gmm-utils mailheader pcvs-util add-log with-editor
async-bytecomp async server subr-x dash evil evil-keybindings
evil-integration undo-tree diff evil-maps evil-commands reveal flyspell
ispell evil-jumps evil-command-window evil-types evil-search evil-ex
shell pcomplete comint ansi-color evil-macros evil-repeat evil-states
evil-core evil-common windmove thingatpt rect evil-digraphs evil-vars
doom-oceanic-next-theme doom-themes doom-themes-base disp-table
whitespace paren time-date warnings mode-icons advice color hl-line
hl-todo time linum company-oddmuse company-keywords company-etags etags
xref project ring company-gtags company-dabbrev-code company-dabbrev
company-files company-capf company-cmake company-xcode company-clang
company-semantic company-eclim company-template company-bbdb company
pcase diminish cl-extra help-mode edmacro kmacro use-package
use-package-ensure use-package-delight use-package-diminish
use-package-bind-key bind-key easy-mmode use-package-core finder-inf
info package easymenu epg-config url-handlers url-parse auth-source
cl-seq eieio eieio-core cl-macs eieio-loaddefs password-cache url-vars
seq byte-opt gv bytecomp byte-compile cconv cl-loaddefs cl-lib tooltip
eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel
term/ns-win ns-win ucs-normalize mule-util term/common-win tool-bar dnd
fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page menu-bar
rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote threads kqueue cocoa ns
lcms2 multi-tty make-network-process emacs)

Memory information:
((conses 16 731956 42472)
(symbols 48 50791 1)
(miscs 40 124 356)
(strings 32 190502 4147)
(string-bytes 1 5360017)
(vectors 16 83436)
(vector-slots 8 1273847 25714)
(floats 8 891 293)
(intervals 56 401 0)
(buffers 992 14))