Measurement 'finished' before unmasking of parameters is complete

[maij]

This is notable when you are doing large voltage sweeps, and the final thing is to reset a gate to a very different voltage.
If the measurement is running in a thread, then the parameter will be unmasking, but the progress bar widget says the measurement is finished before this is actually complete.

The measurement being cleared as the active measurement should take place after this has finished.