Scenario:

-- MySQL datasource with 5000+ records

-- Table contains records of type VARCHAR2

-- One of the VARCHAR2 fields contains text which ended with the \ character.  Eg.  abc\ 

-- The datasource only partially refreshes (approx 3000 records), stopping at the record with the \ character.  No error message displayed.

-- Clicking "Download Data" on the datasource page produces an Excel file with all 5000+ records.

-- Workaround was to add a trailing space to the record in the database!