The bug concerns tab-line.el and you can find a discussion about it here: https://github.com/thread314/intuitive-tab-line-mode/issues/6

 

Here's how I configure tab-line:

#+begin_src emacs-lisp 
  (use-package tab-line
    :ensure nil
    :config
    (global-tab-line-mode 1)
    :bind
    ("C-<prior>" . tab-line-switch-to-prev-tab)
    ("C-<iso-lefttab>" . tab-line-switch-to-prev-tab)
    ("C-<next>" . tab-line-switch-to-next-tab)
    ("C-<tab>" . tab-line-switch-to-next-tab)
    :custom
    (tab-line-new-button-show nil)  ;; do not show add-new button
    (tab-line-close-button-show nil)  ;; do not show close button
    (tab-line-separator " ")  ;; set it to empty
    )
#+end_src

 

The issue is that no tab appears before I do one of the following keybind : C-<prior>, "C-<iso-lefttab>, C-<next>, C-<tab>.

This bug only occurs when the keybindings are specified inside use-package. If the keybinds are specified outside of use-package, the bug disappears:

 

#+begin_src emacs-lisp 
  (use-package tab-line
    :ensure nil
    :config
    (global-tab-line-mode 1)
    :custom
    (tab-line-new-button-show nil)  ;; do not show add-new button
    (tab-line-close-button-show nil)  ;; do not show close button
    (tab-line-separator " ")  ;; set it to empty
    )
    (global-set-key (kbd "C-<prior>") 'tab-line-switch-to-prev-tab)
    (global-set-key (kbd "C-<iso-lefttab>") 'tab-line-switch-to-prev-tab)
    (global-set-key (kbd "C-<next>") 'tab-line-switch-to-next-tab)
    (global-set-key (kbd "C-<tab>") 'tab-line-switch-to-next-tab)
#+end_src