IdeaVim has a few issues due to being thrust onto another application. E.g. Ctrl-V pastes from the clipboard instead of entering visual block mode. Also, it sometimes doesn't process input in order. E.g. pressing Esc Shift-O will sometimes type an "O" before exiting insert mode instead of creating a new line above the cursor. Also useful features that aren't basic movement tend not to work, like text reflowing with gq.

I have a hot key for opening the current file in an actual vim instance whenever I want to write multiline text or use visual block mode.