Myself and the Mrs share a smartbike so we are never Zwifting at the same time.
When one of us starts, the other used to get a companion app notification that they had started Zwifting (this was handy as we could respond with a Ride On for encouragement)
This stopped working a couple of weeks ago and we no longer get notifications when the other starts Zwifting.
We are using the Windows version on a PC for our main Zwift machine and we use android phones with the companion app.
Anyone else experiencing this - It must be an issue as its stopped working for both of us simultaneously.