They had values driven via a rule in RM from a weather device that stopped working so maybe this is how they ended up with null values. Anyway, if I try to now manually set their value I get the following error message:
Would it be possible to override this error and still allow a value to be set please? Otherwise I guess I have to nuke these variables and start again?, which is a pain because they are referenced elsewhere.
Here is the rule that sets these from the weather device (which is now working fine).
It's not at all clear how null ended up in that in the first place, as the hub will generally not send an event with a null value. Whatever driver you are using needs to be fixed.
As for recovering RM, I can see where the problem lies, and clearly RM was not expecting a null value. I've put in a fix for that. So one option you have is to wait for the next release, and then it should allow you to edit the value.
You could try creating a rule that does nothing more than set the value of that GV, to fix it. I don't know if that will throw an error or not. If it does, please post a screenshot of the logs for it.