TRichView.com

Using your Editor2 as an example. Using a Windows or iOS build, this works fine, but on Android it doesn't.

Type in some text. Click the bold button on the toolbar and start typing. On Windows or iOS, everything you type afterwards is in bold. On Android, the first letter you type is bold, then as you type that first letter is no longer in bold, nor is anything else you type in bold. This is true for any of the text attributes, Italics, etc.

What version of TRichView and Delphi?

Sorry, forgot to add that.

Delphi 12.3
TRichViewFMX v23 downloaded June 30 from the link provided upon purchase.

It worked as expected when I tested this demo. Probably, something was changed on one of Delphi 12.x updates.
Unfortunately, I was not able to check this problem yet. And I will be on vaсation till August 5th. I'll fix this problem when I return. Sorry for the delay.