You might try exporting your data to text files, then importing from the text files into a clone. That sometimes resolves an issue with the data.
Recently, I figured out that my problem is in one particular field. However, I don't know what about the field is causing the problem. It is a large text field that is made up of copied and pasted data. I've tried stripping off the formatting (differing text sizes, colors, fonts, etc) and still had the problem. I tried replacing the text with serial numbers, and that seemed to work (telling me only that the isn't some inherant formatting of the field). And it SHOULDN'T be that there is too much text in each entry, since the field size limit is "up to 1 billion characters per field per repetition" according to http://help.filemaker.com/app/answers/detail/a_id/7541/~/technical-specifications-of-filemaker-pro-11-and-filemaker-pro-11-advanced
.....does anyone have any ideas?
Try using replace field contents on this field with a calculation option that filters out all text except what needs to be there.
Filter ( textfield ; "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" )
For example will strip this field down to just the digits 0 - 9 and the letters a-Z. If you add some additional characters, you can modify this to also include spaces, basic punctuation and return characters.
This worked! Thank you so much for your help!!!