It just says, "Phone not formatted properly", but there isn't anything in the support documentation to designate what a proper format is. In addition, the mapping itself is too brittle. The importer should catch any malformed phone fields and spit them out, rather than blocking an entire import due to a single bunk field.

The solution appears to be to filter the list, to ensure that the top 10 rows do work, so that the bad rows can be filtered out later. But, this should be in the documentation and suggested to the user as a part of their import prep.