Bias is only available on the front panel microphone connector. The XLR/TRS does NOT have any bias connection.
There are two sources for Bias on the 8-pin Foster connector:
There is an always on 5V sourced through a 560 Ohm resistor to pin-2 as shown below.
You can also turn on the Mic Bias in the GUI that turns on a 2.97V source that is applied to pin-8, which is the microphone hot lead.