I tested it in 21.1 preview 4 #17067 and it didn't seem to work.
Although I have an error when setting the low-level property ignore.supportTrackedDir the value is correctly set to true (The bug has been reported) but I still can't ignore a directory with staged files or missing directories in it.

Also it is impossible to Ignore a directory if a file in this directory is staged.

Hello, thanks indeed I didn't knowthat it was possible this way.
I believed it was not implemented since I was expecting to see it in the Ignore window and I don't show Directories in the Files view.
Do you think that would be possible to integrate it in the Ignore window?

Actually the core.autocrlf was already set but what was needed is safecrlf:
git config --global core.safecrlf false
Thanks, now I won't be annoyed by this warning again :)