side loading – Keyboard won’t open for sideloaded apps on my Sony Bravia VU1

I’ve sideloaded both Chrome and Firefox on my Sony Bravia VU1. I have LeanKey Keyboard installed as the default keyboard and it works fine everywhere in the system except in Chrome and Firefox. All I get onscreen in those apps when trying to type is an input box with a microphone symbol to the left, but it disappears after about half a second. Based on other posts I’ve removed the GBoard app updates, but that had no effect. Also, this behavior is the same whether the virtual keyboard is enabled or not.