Reproducing steps:
1. emacs -Q
2. M-x blink-cursor-mode
3. menu-->Options-->Set default font-->choose a bigger size
4. M-x load-theme light-blue
5. switch to other app and then back to Emacs
6. The color of the cursor doesn't restore.
7. After a mouse click in the emacs frame, the cursor color restores.



In GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin17.7.0, NS appkit-1561.61 Version 10.13.6 (Build 17G12034))
of 2020-04-10 built on jundeMac
Repository revision: e18c24b35a7cf9bb1b91288b706fa448ed28a7c2
Repository branch: master
Windowing system distributor 'Apple', version 10.3.1561
System Description:  Mac OS X 10.13.6

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Blink-Cursor mode disabled
funcall-interactively: End of buffer [7 times]

Configured using:
'configure --with-mac --with-modules --disable-acl --without-makeinfo
'CFLAGS=-O2 -g0''

Configured features:
RSVG GLIB NOTIFY KQUEUE GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS
MODULES THREADS JSON PDUMPER LCMS2 GMP

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

Major mode: Lisp Interaction

Minor modes in effect:
 tooltip-mode: t
 global-eldoc-mode: t
 eldoc-mode: t
 electric-indent-mode: t
 mouse-wheel-mode: t
 tool-bar-mode: t
 menu-bar-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
 line-number-mode: t
 transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
epg-config gnus-util rmail rmail-loaddefs text-property-search seq
byte-opt gv bytecomp byte-compile cconv mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils time-date subr-x
cl-loaddefs cl-lib cus-start cus-load light-blue-theme china-util
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
tab-bar menu-bar rfn-eshadow isearch timer select scroll-bar mouse
jit-lock font-lock syntax facemenu font-core term/tty-colors frame
minibuffer 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 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 52410 13532)
(symbols 48 6858 1)
(strings 32 17060 1106)
(string-bytes 1 524325)
(vectors 16 9827)
(vector-slots 8 183804 8540)
(floats 8 20 46)
(intervals 56 183 0)
(buffers 992 10))