Channels disappear and later reappear

Frequent issue for some of our team members, where channels suddenly disappear, only to reappear later (sometimes within minutes, sometimes days later). The channels are not searchable when they disappear, and starred channels also disappear. Logging in and out does not seem to have an impact.

Sometimes the channel will remain accessible through the mobile app, other times it disappears from all logins, vice versa. 

Tagging/direct notifications are still received even when the channel has disappeared, however clicking on the message does not bring back the channel or allow the user to reply. 

Seems like other users have had similar experiences and no solution as of yet. Makes the chat function almost unusable for our team. 

Thanks