Certainly, I understand not. Are you seeing this issue only in Reaper, or in other DAWs as well?
Also, if this happens again, can you double check to see if the UltraChannel effects are still working, or if the plug-in is just outputting the tone now? Also, I'm curious if the UC effects themselves effect the tone, or if it's coming from after the effects.
I can follow up with you offline as well. Would you mind emailing this to email@example.com and asking for Dan Gillespie?