ERROR: 3/28/2016 9:15:08 AM :: Error: Cloud repository Cloud repository 2 is unavailable due to the service provider restriction.
When I went into Backup Infrastructure / Backup Repositories and told it to Rescan repository the issue corrected itself.
My thoughts are that B&R checks at some interval and sets a flag that the repository is bad. The Backup Copy jobs keeping hammering away because they see that flag, fail out and try again.
Should there be some logic that says rescans the repository after a number of failures or a way to configure rescans more often?
The said issue suggests that there have been problems on your SP's side, like underlying repository becoming unavailable for some reason or similar.
Backup copy job has in-built logic responsible for rescanning both SP and its cloud repositories, though, under rare circumstance it gets confused while facing unavailable cloud repository. Chances are, you have come across that problem and manual rescan addressed that.