Power dropouts while climbing only

My partner and I ride together frequently. We both have the same trainers - Elite Suito and the same power pedals - Assioma. She’s connected to her Ipad directly with BT. I’m using laptop and Zwift Companion to connect. Here’s the issue:
When ever she gets on any kind of a sustained hill her power begins to dip up and down. She’ll be holding 260 Watts and then suddenly down to 120 for 4-5 seconds. She’s a strong rider who can put herself into QOM with some frequency but these dropouts are killing her. It’s only on the hills.
I looked at her power files and the pedals aren’t dropping.
I’m having no problems with my set up.
Any ideas?

maybe the trainer is overheating? Some users have found they need a fan just for their trainer so it doesn’t overheat.

I wonder how I would test that out?
It’s pretty cold where we are and we’re out in our garage. So it’s usually 4-6 (40-44) degrees ambient.
But it’d be easy to just pop a fan on there and see if it helps! Thanks.