Midi playback changes patch

[alathosco]

(Windows 10, 12gbRam - uptodate with Reaper)

I have a midi track I plugged in RealControlMidi into. I loaded Genl Midi & picked the Woodblock patch. I set the Midi Hardware Output to 'Microsoft GS Wavetable Synth'. Went to Piano Roll. There I swept up and down its keyboard and heard the Woodblock sounds. I popped in some notes then when I played that back - the output sound was a piano!?! I tried moving the plugin to both FX junctures to no avail.

After that, when I sweep up & down that piano roll keyboard - it then sounds like a piano. I have to remove the plugin and reapply it to get the keyboard to resound like the Woodblock choice I made - but everytime I play back the notes - they get changed to a Piano.

Why is it doing that? What is overriding the patch?