Editable number buttons are not responding in Firefox

[Philly-B]

Hello,

Bug description:
basically the title says it all. I'm using angular-xeditable (in version 0.7.2, but it still seems to be broken in current version as well).

The screenshot is taken out of a minimal fiddle I created to reproduce the bug. The fiddle can be seen here: fiddle. The buttons work as intended in Chrome or Chromium.

Additional information:
The buttons start working when I remove the bootstrap-min.css resource (however, styling is obviously broken afterwards).
More specific: The form-control class seem to mess up the functionality of the buttons. By removing the form-control class of the input element, the buttons start working again. Digging even deeper: The form-control class adds a padding to the input, which somehow blocks the buttons since removing the padding (padding-right) is enough to make the buttons work again. This can be observed in the following updated fiddle

Expected behavior:
I expect to edit the number in the field by pressing up or down arrow button on the right side. They seem to not respond.

I'm using a current Firefox in version 88.0.1.

Any idea on what is going wrong here?!