Is balance due a field of type calculation or a field of type summary?
Your issue report title indicates that it's a summary field, but the layout suggests that it may be a calculation field.
If it is a calculation field, please post the calculation.
Since you are certain that nothing has changed, take this file or a very recent back up copy and run a recover on it. Perhaps the file has become damaged in some way.
Things to keep in mind about Recover:
While Recover almost always detects and fully corrects any problems with your file...
- The recovered copy may behave differently even if recover reports "no problems found".
- Recover does not detect all problems
- Recover doesn't always fix all problems correctly
- Best Practice is to never put a recovered copy back into regular use or development. Instead, replace the damaged file with an undamaged back up copy if this is at all possible. You may have to save a clone of the back up copy and import all data from your recovered copy to get a working copy with the most up to date information possible.
And here's a knowledgebase article that you may find useful: What to do when your file is corrupt (KB5421).
It says it is a calculation - see two more screen shots attached. Let me know if this changes the way to approach fixing this problem.
Do you see this only on this record?
Here's what this looks like:
If you enter a date into a text field and then include that field in a calculation, you'll get the digits from the date field as shown in this post.
If you enter a date into a number field and then use that number field in a calculation such as adding 0 to it, you'll get the digits of the date also.
I'd check the value of each and every field listed in that calculation by clicking into the field and checking for data. By clicking into the field, you check to make sure that the value isn't hidden by having a return put it on a different line than the single line visible on your layout.