Select Mode problem with completion engines

[jfab20]

Expected behavior: Automatically triggered nested snippets that work well with completion engines

Actual behavior: Described in https://github.com/SirVer/ultisnips/issues/1327 and in https://github.com/SirVer/ultisnips/issues/1380

Basically completion engines ruin nested snippets that are triggered automatically

Steps to reproduce To reproduce this just install one of the following completion engines:

• Deoplete
• nvim-compe
• coc-nvim

Then install Ultisnips, and create the snippet

snippet test "test" iA
\test{$1}{$2}$0
endsnippet

Then just nest like 5 test snippets and jump to the next placeholder repeatedly. This happens:

The new thing I have noticed is that:

• This bug disappears if you make the snippet don't trigger automatically (that is, just give the option i instead of iA)
• If I do :smap with deoplete disabled I get this two mappings which weren't present when the engine wasn't installed, maybe it has something to do with that. The bug seems to happen when I'm in select mode

I still have no solution to this and it is very frustrating because I cannot use ultisnips with any other completion engine :c Hopefully someone finds at least a workaround

This is the vimrc:

call plug#begin()
Plug 'SirVer/ultisnips'
Plug 'Shougo/deoplete.nvim', { 'do': ':UpdateRemotePlugins' }
call plug#end()
let g:deoplete#enable_at_startup = 1
let g:UltiSnipsExpandTrigger="<tab>"
let g:UltiSnipsJumpForwardTrigger="<tab>"
let g:UltiSnipsJumpBackwardTrigger="<s-tab>"

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• Operating System: Arch linux
• Vim Version: nvim 0.5
• UltiSnips Version: 3.2
• Python inside Vim: 3.9