I had a situation where multiple databases (50+ Databases) changed to Suspect mode.
Simple solution: (assume the DBs are in Server-A, Availability group and Server-B is configured as secondary server)
* Fail over the availability group to Server-B
* Resume Data Movement in Server-A
* Fail back the availability group to Server-A
Other references to fix the problem:
Note: Used Object Explorer Details (F7) option to resume data movement on multiple databases: https://vijredblog.wordpress.com/2018/07/10/how-to-operate-multiple-objects-in-ssms-f7/