I just opened support case 00879340 and I wonder if anyone else has seen this.
I installed 18.104.22.1684 yesterday and set "Backup no more often than every" = 90 minutes
I set Daily = 12:30 PM and at Lock and "When backup target is connected"
I ran a backup manually at 12:10 but the 12:30 backup also ran. I think I had "no more often than every" = 2 Hours with the RC, and it worked.
I'll try to remember to test it again tomorrow.