VESQL database restore to Always On Availability Groups with automatic seeding enabled is hanging

Challenge VESQL database restore to Always ON Availability Group with automatic seeding enabled SQL 2016 SP1 and later does not work. Veeam SQL Explorer log shows repeating records like: 10/23/2017 8:19:22 PM 11 5160 SQL query: ALTER DATABASE SET HADR AVAILABILITY GROUP = 10/23/2017 8:19:32 PM 11...