Linux Bodhi 6.0.0. Tab deletion does not work: neither Shift+Tab nor Alt+}. How to fix?

Question

linux

Does not work in any program. Autoformat doesn't solve my problem. tabs should be formatted, incl. plain text (i.e. not only in the IDE, but also in notepads).

In the Bodhi system settings in Settings -> Input -> Key Bindings, I did not find an option that had anything to do with tab or unindent.

Is it possible to somehow assign a shortcut from under the terminal or in another way?
Or perhaps there is another solution to this problem besides remapping?

I googled and searched inside Habr QnA. But, alas, I did not find a ready answer.

Clarification after comment @hint000
Conventionally, we have three lines, of which the first two are separated from the left side by a tab.
Here the layout flies, so I will designate the tabulation as ____

abc
____def
____ghi

I select with the mouse or from the keyboard with the cursor while holding Shift these tab-separated lines

abc
____def // вот эту 
____ghi // и вот эту

I press Shift+Tab or Alt+}. I expect that, as it was in any program under Windows, the reverse of tabulation will occur - i.e. Shift the selected lines one tab to the left. I.e.:

WAS

abc
____def
____ghi

BECOME

abc
def
ghi

Instead, what happens... nothing happens. Regardless of the program in which the action takes place. Again, under Windows it worked literally everywhere. If I remember correctly the events of a year and a half ago, this also worked under Linux Mint.
The keys are working, other combinations with them work fine.

Answer 1

The problem is resolved. Unexpected source: gXNeur. Shift + Tab is assigned to some useless (for me) and imperceptible function during random use.
Disabled these hotkeys in gXNeur - it worked.