The "Range Bands" field on the class design display accepts the return key/new line characters as input. If you accidentally enter one and then try to modify the design or open a different class design, you'll now constantly get the error "1.12.0 Function #237: Input string was not in a correct format."
Depending on where it's put, the user may not know that this is the problem. The range band by default has a value of "10000" I had clicked into the range band field and entered 40000, but thinking I needed to confirm it I hit return with the cursor just after the 4, which changed the displayed value in the field to "0000." I entered 4 again and clicked out, with range bands now showing "40000," but constantly getting the above error no matter where I tried to navigate. I had to go back into the Range Bands field, and delete back to the beginning to clear the newline character out; the field accepts multi-line inputs but only ever displays a single line, so the user can't tell by looking that the new line is the problem if they hit enter a few times.