In the case of dimension-only queries, users observe that the 'where clause' is completely missing on the outbound queries generated by the AtScale engine like in the below example.
Note that the inbound query has a clear 'where clause' which restricts Year to 2005 and Quarters to 1 and 3, but those filters are entirely missing on the outbound query.
RESOLUTION
If the above scenario happens consistently across the environment, please navigate to SETTINGS --> Engine and search for a setting "QUERY.FACTLESS.IGNOREINCIDENTALFILTER". This setting should be set to "False". If it is set to "True" the AtScale engine Ignores the 'where clause' in dimension-only queries.
Where Clause Ignored on Dimension Only Queries
Where clause Included on Dimension Only Queries