I'm just guessing, but maybe you have a "<" character in one of your field names. If you keep special characters out of field names, then expressions and sync/import/export tools run work much better -- any function that causes external applications to use the field names as column names of a spreadsheet or that causes an expression like "field == <field2>" to be evaluated.
I name all my Boolean fields like Done?. It almost always works, so long as I don't sync, import, export, or use the field in an expression, like in a Calculation field. Even then, it works most of the time -- maybe OK for one tool, but not for another -- but sometimes it just won't.