Ahhhhh. Indeed there might be something leftover. Anyway, if that’s the case, it’s a bug I’ll forward to dev.
Backup and restore of 2.5.0p3/p4 works very well on the command line with omd backup and omd restore. I just hope, the leftover is in the config for the omd command. Experiencing the same issue on a freshly created site seems to point in that direction.