Here is an image. In every state I get a variable from the stage FSM I use the StageNr variable as the name. It gets assigned the correct name every time so there is no problem there.
I've tried changing the name manually to different stage names and it works, the first time, so it gets data correctly. I even tried with a non existing name and got warnings that those variables doesn't exist as expected.
Here is what's strange though. If I do a stage trigger and then remove the StageNr variable and do a new stage trigger, you would expect it would look for a non existing FSM, but it doesn't. It gives no warnings and it does a normal stage transition, but of course to the same stage.
This makes me almost 100% certain the FSM name gets locked after the first time the Get FSM X is run.