Form Recognizer - training of custom model keeps failing

Question

I keep getting an error saying 'ModelBuildError: Could not build the model: Can't find any valid labels for provided dataset. Labels file file.PDF is invalid for the following reason(s): 'Label names are incompatible with the content of fields.json and the label schema version.' ...all files listed here in the same way... Cannot use fields.json; All labels are processed as normal key-value fields. Subfields of Table are not with the same fieldType.'

But the labels seem fine and the fieldType is set the same for all sub-fields of the tables on my documents. Do you know how I could fix it?