I'm having the exact same issue, maybe after updating my Macbook Air to the latest beta OS version. I'm even unable to reset factory setting, when I click that option, nothing happens. Really annoying :(
I had the same issue. Found out that the Stereo Delay block in my preset was the problem. As soon as I removed it from my chain, all snapshots started working well. I love that delay model, but I asume it's not working well after 2.81 update.