Here’s a weird one. The ADF’s power state is coded to the KAP 150 head unit’s power state. In other words, if the ADF is off, the KAP 150 head unit is off and likewise if the ADF is on, the KAP 150 is on.
You can see this on the ground, easily. Spawn C&D, power up the aircraft and avionics and then, with the ADF off, press the KAP 150’s test button and note nothing lights up on the display. Now, turn on the ADF and then press the KAP 150’s test button and note now it lights up.
I’ve also added clarification to this bug report regarding the AP’s behavior with and without the WT GNS 530 add-on installed. The WT GNS is absolutely breaking the behavior of the KAP 150 and KAS 297 units on this aircraft. This has to be addressed by Microsoft – their aircraft and their avionics improvement to the sim are in conflict.