Swallows first letter

[Boelensman1]

Thanks for the awesome plugin!

However I have a problem that makes it very hard to work with.
Right now whenever I start typing something the first letter of whatever I type disappears.
So for example, I go to insert mode, type the letter a. The a goes away and the autocompletion opens. Any subsequent typing while the completion window is open works fine.

It seems to me that the opening of the autocompletion (not sure what to call it, the window that has all the choices), removes whatever you typed.

[chemzqm]

Seems like conflict with other plugin, try to filter your plugins to see which one cause the problem.
Coc would not change your buffer unless completion is done with confirmed.

[iamcco]

the completeopt option has longest will occur this

[chemzqm]

I can reproduce it, it happens sometime.