Cannot save notes

[Japandave]

So here is a new issue for me.

nvALT has been working perfectly since the High Sierra fix a few months ago, but suddenly, yesterday, this started. No sooner have I opened nvALT than I am faced with these popup errors every few seconds. To wit: "Changed notes could not be saved because there was a problem accessing the disk media"

If I try to quickly edit a note between error messages popping up, it won't save any of the edits.

Er... what happened? The most recent app install I did was a few days ago when I upgraded to the latest high Sierra beta. But that was a few days ago and the problem didn't start until yesterday. I have reboot. I also turned off syncing. (it is on in the photo, but even when I turn it off I still get the errors) Still having the errors. Any ideas??