Preview problem

When I open glyphs the preview mode works, after about 5 min. it doesn’t work anymore. The only way which helps is to restart glyphs, but it’s a bit annoying. Does anybody know a solution?

There is a hidden bug that I could not jet find.
What did you do before the preview breaks?

Thank you Georg, probably it was one of the last update? not sure, when I had it before (several months ago, it was a problem with a plug-in, when I deactivate all plug-ins, it seems to work.

Did you close an inactive tab with the mouse?

no, it happens during the work, at a certain moment it doesn’t work anymore and I couldn’t notice why