Sorry for the late reply.
I do remember to have seen this before: “The server understood the request, but will not fulfill it. – Could not get FIELD information for …” It occured with a relatively old MySQL 4.1.x too and was not reproducable with 4.1.20. But I do not recall details.
Also we just verified that 4.1.19 (and 4.0.20 and 4.0.21) and 4.0.26 (and 4.0.27) syncs.
But it could also be an issue with a specific character set or data type.
Please create a ticket with some source data (only the problematic table with a few rows of data)