I'm using Dolby Surround as my default mixed, and with Dirac enabled, both Bass and Treble work just fine.
It may relate to what mode the AVR is in, I have not experimented with all the possible combinations - some, like THX, disable Dirac....
I have tried in stereo - with Dirac enabled, and it worked fine.
Final note/caveat: - I am using an Integra DRX 3.4 - most of the firmware is identical, as are most of the modes/dependencies etc... but not all - I would not expect this to be different between them.