Please open Settings | Plugins (Host) | Installed tab, and make sure the IdeaVIM plugin is not installed or enabled there.

Also, make sure the IdeaVIM is installed/enabled in Settings | Plugins | Plugins (Client).

Currently, the IdeaVIM doesn't work on the host side when using remote dev.

See https://youtrack.jetbrains.com/issue/VIM-3334 for details.