I went down this rabbit hole four years ago. My only conclusion was to use one power meter for training. Bypass the trainer’s power meter at all costs. If you really train on two bikes, then get power meters (like pedals) that can be adjusted to match each other.
I also found out that my Stages performs way better with more expensive, retail pack Duracells. Cheap 10 packs off of Amazon sucked. The Stages is probably voltage sensitive.