After running the Schema Sync Tool, I then ran the Database Sync Wizard, which reported (from the log): Column definition mismatch for 'bp_id' column in '`bp`' table.
On closer examination, I found that the PK column of the table in the Target database was not set to AutoIncrement as it should have been. I retried the Schema sync several times, but it found no differences.
I regularly use both the Schema and Database Sync tools, and they've been bullet-proof until this one error. Just thought I should mention it.