iPad Pro IPP 10.5 split keyboard doesn't work in 3rd party apps

[iosuser]

I just noticed this. It seems all Apple apps are fine, but most if not all 3rd party apps split keyboard is not available. The lone exception is YouTube which does work. Happened on 10.3.2 and just updated to 10.3.3 with no change. In those apps where split keyboard is unavailable, the keyboard flickers when I press the shift key. There's definitely a bug in there. Has anyone else noticed this?

Tried it on the Mini 4 and an Air 2 here and they're fine, so it seems only the iPP 10.5 is affected.

 

[iosuser]

Updated to iOS 11 on my 10.5 iPP. Split keyboard still doesn't work in pretty much all 3rd party apps, the lone exception is still YouTube. I guess the individual apps have to be updated, as I had originally suspected.