elpy and evil-mode do not react on TAB

[c.buhtz at posteo.jp]

X-Post:
https://emacs.stackexchange.com/q/61497/12999
and
https://lists.gnu.org/archive/html/help-gnu-emacs/2020-11/msg00061.html

Hi,

my problem is that the TAB key does nothing in elpy (python) mode and
evil-mode also.

This is my elpy-config

>  1Elpy
>  Configuration
>  2 3Virtualenv........:
>  None 4RPC Python........: 3.7.3
>  (/usr/bin/python3) 5Interactive Python: /usr/bin/python3
>  (/usr/bin/python3) 6Emacs.............:
>  26.1 7Elpy..............:
>  1.28.0 8Jedi..............:
>  0.17.2 9Rope..............: Not
>  found 10Autopep8..........:
>  1.5.3 11Yapf..............: Not
>  found 12Black.............: Not
>  found 13Syntax checker....: flake8 (/usr/local/bin/flake8)    

It runs on Debian 10.

When typing TAB nothing happens. No message. No change in the mode line
or status line. I would expect 4 empty chars when typing TAB.

 M-x describe-key TAB results in

> TAB (translated from <tab>) runs the command evil-jump-forward (found
> in evil-motion-state-map), which is an interactive compiled Lisp
> function in
> ‘~/.MyAppData/emacs.d/elpa/evil-20201014.2043/evil-commands.el’.
> 
> It is bound to TAB.
> 
> (evil-jump-forward &optional COUNT)
> 
> Go to newer position in jump list.
> To go the other way, press C-o.  

I have evil-mode installed and activated. So there must be a reason why
TAB is used by evil-mode but do not work.

btw: I am quite new to emacs.

kind
Christian