Substance Painter is not responding after creating smartmaterial

I'm using Painter for many years but that never happened to me before. I'm creating a material, some painted layers, some fill layers with anchors. Additionally I have opacity and emission channels in some of my layers. Material isn't particularly complicated or complex, but first problem is that Painter starts to be laggy and responds very slowly (with 1024px texture, that's not possible to be laggy at all). Second, after saving smartmaterial (I wanted to reuse my material later) it does... nothing. I'm not able to do anything more, the loading bar just under the viewport is stopping on 100% progress and that's all. Newly created smartmaterial doesn't have a thumbnail, and the funniest part is that if any of the other smart materials weren't loaded before creating my new smart material, they won't load (I mean, theirs thumbnails, but nothing can be done at this time, I can't add new materials, do anything, nothing is happening). Two or three times when I was closing the app (or maybe more like force-quit), on every part of the ui (viewport, UV space, Assets tab and Layers & Properties) black triangles appeared for a second. Don't know what that was either.

I'm using the latest 7.4.3 version (Steam) on Windows 10. My PC has very good specs and as I said, it never happened to me before (even with much more complicated projects). My drivers are the newest too.

Can't really send the file to the forum because that's a work for a client and I don't want to share it although it's nothing very big.

EDIT: worked after reopening and resaving the file again.