Style menu greyed out for no apparent reason (S3)

At seemingly random times the styles section of the menus becomes greyed out in S3. Styles can still be selected from the Styles panel and from the dropdown menu on the formatting bar, however keyboard shortcuts don’t work when the menu is greyed out.

I can’t put my finger on what triggers this but it has happened to me a few times now. The only way to restore it is to quit and restart the application, or sometimes it just becomes active again of its own accord.

I can’t think of anything that would cause this unless there’s an error getting thrown in the background. I you can find any way to trigger the issue, that would be really helpful.

Thanks and all the best,
Keith