Thanks Lars.
I think our posts crossed. This only appears to affect Analytical views with calculated attributes - so I don't believe I can provide the code to reproduce.
As per my second post, the issue seems to be in the CALCULATION SCENARIO view in _SYS_BIC. The sqlType and Length of our BIGINT measure (from the data foundation) is being incorrectly generated as "sqlType": 4,"sqlLength": 9.
I have calculated BIGINT's in our Analytical View which are correctly defined in the CALCULATION SCENARIO as "sqlType": 34,"sqlLength": 18.
I know this is a very specific issue so not easy to reproduce!
cheers