When applying a filter on one of the table columns in Data tab of Object Explorer, Toad is not returning all rows. If user performs a Select statement or does a Define Filter with same criteria, Toad shows all rows that should return for that criteria from table. Toad 4.7 does not have this issue and issue occurs only on certain tables.
Use Ctrl+End keys and wait until all rows in Data tab are loaded prior to applying the filter.
Waiting for fix to be released in a future version of Toad for DB2.