Install the old leanback keyboard
Disable Gboard (in settings>apps), turn on Leanback Keyboard, turn off Virtual Keyboard (settings>Manage Keyboards or something like that).
Enjoy.
Edit: Third party remotes that work with a USB dongle this is for. You were able to navigate and select with them, but no text entry (in search fields for example) was possible.
Holy shit. I been having this fucking issue with a Amazon FireTV remote. Is this only on Nexus player? And what is the actual cause?