Well generally in my case when an overflow problem happens it's because of the pitchbending boxes. When you convert from VCV to CV, naturally the pitch boxes will become a bit distorted, because average VCV notes/sounds are generally much larger than average CV notes (due to the beginning vowel) and so when you use a CV bank instead, the pitchbending boxes will be stretched into places that normally wouldn't fit CV notes.
The best advice I can give you is to select all of the notes, right click and select the "Pitch" option, uncheck the very first checkbox at the top and then click OK. The downside to this is that you're going to lose any complicated pitchbending the UST may have had.
If you want, you can just test note by note to see which individual notes are causing the actual error and just clear that box's pitchbends too.
If that doesn't help, what I suggest is again, selecting all of the notes in the UST, right click, and this time select the "Region Properties" button. If the Preutterance, Overlap and Consonant boxes are grayed out, put a space in them and click OK, and that should clear any settings the UST maker put on for the notes.
That's the best advice I can give, sorry if it isn't useful ;x;