Hi Please check your universe Parameter option
In that make sure that the option Multiple SQL queries for each measure object.If the above one is selected then you wont encounter chasm traps.
Please refer to the following thread
https://bobj-board.org/t/77439
I have tried with the same scenario without creating the contexts but still i got the correct count.this is due to the reason the option is selected default. and hence no job for you to create the aliases / contexts.
Thanks,
KK
karlak (BOB member since 2006-11-01)