As sometimes is the case, just entering my question on this forum causes me to look at the problem again, and I've solved my own problem.

First, I found that the K-1 not included in the carryover 179 totals WAS actually included. I had entered it my manual list twice. The error was mine--not ProSeries.

I was finally able to go the the CA Schedule K-1's and determine the necessary amounts for line 12c and entered zeroes in anything over the $25,000 limit. Finally, the error went away.

To quote the famous Emily Latella:  "Never mind."