I noticed this the other day, but thought it was just a bad mesh. I was in a hurry, so I just sliced it with another program.
Now, I'm starting to see it pop up more and more. For some unknown reason, when I use certain layer height/resolutions, it gives me a solid top layer, technically defined as a bridge. I've attached two images. This is the same model. I've gone up and down each and every tab, to see if anything other than layer height was different in the settings. I found nothing. I checked multiple times, just to be sure. The model is as it should be in the 0.2 layer height image.
I've also been experiencing some models that are solid on the main screen, but when going to the slice preview, shows gaps in the middle of the print. Again, solution was to just use a different slicer.
I don't know if I somehow managed to change some secret settings, but if anyone has any suggestions, I'm all ears. The solid top layer is priority #1. I haven't had a chance to check the mesh for errors/gaps on the odd gaps in the middle, so that's low priority.
Thanks!