I worked mine out. It had to do with the system mis-typing my variables after saved and recalled. I could delete the statement, and paste it back in and it would work fine again, until saved and reopened. The total fix was to set my variables explicitly to Text() when defining them the first time. Despite the data source column clearly being a string, it was improperly interpreted. Automatic variable initialization is not always your friend.
Not sure this has anything to do with your problem, but the issue does seem to be an issue with the editor not doing the same thing in run-time.