As you were. I updated from Bandlab Assistant and it's all working now. Thanks to those involved.
I have the same problem - Mix Recall buttons greyed out and drop-down "save mixscene" does nothing. I ran an update, and ws told "You are up to date! 25.01.0.24 is the latest available version." So I'm afraid the update hasn't worked for me. Pity, as I was hoping to use this on a particularly complex project at the moment.