Messages not being posted and riders disappearing in group rides

I have been having huge issues lately when leading group rides my messages to group will suddenly not get posted with riders not being able to see me. Generally ride starts out well then after 10-15 mins the messages in game do not get posted but I see them in comp app. The group size yesterday was 690. It’s been happening for 3 weeks. Seem to have a lot of glitches with Zwift generally. I have rebooted broadband router and reinstalled Zwift on applet TV and iOS and still problems. Today after 1 hr I disappeared from view from riders around me but I could see them and their messages and they could see my messages. Any thoughts ?? Thx. Jeff