I was building stuff, making some undo sometimes (with Ctrl-Z), then i failed and did an undo twice. So i pressed, in the menu, the Redo button and the software got softlock. No feedback or a Windows message saying i have to wait or something, it was just locked. I wasn't able to close the software with the red cross or anything so i had to shut the process down.
I'm sorry i guess it's a blurry report but... as it apeared i had to let you notice it.
I also think that the save shortcut was still working even if i didn't got any feedback showing.
I hope it helps.