That’s the easy part, if you’re willing to use The DELETE command in GUI Commandline.
The COMPACT command (or button) is the hard spot, as that’s what actually frees space.
The below is meant to avoid that, but maybe you blew right through the last bit in one shot?
–quota-warning-threshold (Integer): Threshold for warning about low quota
Set a threshold for when to warn about the backend quota being nearly exceeded. It is given as a percentage, and a warning is generated if the amount of available quota is less than this percentage of
the total backup size. If the backend does not report the quota information, this value will be ignored.
* default value: 10
The problem with compact is it needs a bit of space to do repackaging to remove wasted space. Previously this was a known amount, not too much, roughly 50 MB default Remote volume size.
Developer fix would be welcome, but lacking that, a procedure to solve would be nice as well.
Possibly you are in a fortunate position where manual cleanup is possible, but that’s very ugly.