That bluetooth feature was removed in the latest firmware.Each output can have it's own EQ, but there are only 4 channels out, so 2 stereo devices.
However there are 4 profiles, and each profile has it's own EQ - There are direct buttons on the remote to select each profile.
Annoyingly it will auto switch to bluetooth when a connected bluetooth device sends it audio - this is a pain in the ass as a connected phone will switch of audio from any other source for a notification sound or similar. So I disconnect any bluetooth device unless I am using it. Otherwise, inputs are selected from the remote but you have to cycle through them - single button.
From miniDSP:
V1.16 Firmware v1.25 / 14th June 2022
- Remove BlueTooth Autoconnect feature
- Fix bug of muted output on bootup for certain conditions on Flex Digital
- Fix bug of incorrect output sample rate metadata bit on Flex digital / 48kHz now showing correctly