Display Error when Rotating Screen (Portrait/Landscape)

I am in the testing phase of my keyboard, and I noticed that when I rotate the phone from portrait to landscape and then back to portrait, a blank area appears above the keyboard:

And then when I rotate it back to landscape again, there’s an even larger blank area:

Has anyone run into this issue?

I am running Keyman version 11.0.2107 on Android 8.1.0.

I’m also running Keyman version 11.0.2107 on Android 8.1 but am only seeing this rotation issue in WhatsApp.

Thanks for making me dig deeper on this. In testing out various other apps, here are some findings:

YouTube, Gmail and Google Search work fine.
Calendar and Hangouts just drop the keyboard every time I rotate. I don’t mind that as much.
Signal and Messages (stock Android SMS app) give the same problem (with a white box instead of a black one).

During this search I noticed two other little bugs (possibly for other threads?):
(1) When the keyboard is out, the buttons which I’ve circled in the picture are unclickable.

(2) The down triangle (which typically drops/hides the keyboard) functions as a back button.