TL;DR: when using s-pen, keyboard does not load.
I finally got some feedback from Samsung the default behavior for One UI 5.1 and going forward...they turned on DirectWrite by default. Which is breaking TV expected behavior.
Issue: when S-pen is out. Selecting the keyboard does nothing. The DirectWrite being on (and with no ability to turn it off) is suppressing the keyboard request event.
Samsung has no desire to revert back to previous behavior. (which is desirable to use the stylist as a mouse.)
Anyway to work around this new limitation?