How to debug change in key binding / command behavior (<c-p> / ctrl-p for ctrlp.vim vim plugin)?

Question

I'm using the vim ctrlp plugin, and the <c-p> (Ctrl+p) key binding / command (which invokes :CtrlP) often goes back to the vim default of moving the cursor up a line. I can't figure out why this is happening. How can I debug this?

(I've been using the vim ctrlp plugin (https://github.com/ctrlpvim) for 5+ years, and this just started happening in the last month. I've updated the bundle to the latest code from 25 May 2020.)

I thought maybe the mapping was getting lost, but before and after this behavior, the mappings are the same:

:filter /ctrlp/ map
   <C-P>         <Plug>(ctrlp)
n  <Plug>(ctrlp) * :<C-U>CtrlP<CR>

And when it happens, I can still use :CtrlP to get the same functionality as the <c-p> / Ctrl+p command that is no longer working. If I exit vim and start vim again, it works again.

Workarounds:

• use :CtrlP

• use Shift+Ctrl+p

• restart vim

   $ vim --version
   VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Aug 20 2020 22:44:15)
  

Update (31 Aug 2020):

It looks like this might be either a vim issue or an iTerm2 issue: https://github.com/vim/vim/issues/6794

Answer 1

This was due to an iTerm2 issue. I'm gone from iTerm2 Build 3.4.0beta4 to Build 3.4.0beta10 and have not been seeing the issue anymore.

See also this related vim issue.