This has been reported occasionally for at least two years. I've never heard a solid explanation about how it happens, and if often goes away if you wait a while and reload the page. However, since the problems have been reported before this Beta Feature became available, it is not caused by the new editing mode.
Topic on 2017 wikitext editor/Feedback
The screenshot was from 17:51:12, how long do I have to wait for this? And I only saw this behaviour in Connection with the 2017WE, but I have to confess, I don't use the VE, because it's loading times are far too excessive. Grüße vom Sänger ♫(Reden) 07:46, 3 February 2017 (UTC)
In my experience, it usually resolves within a few minutes, but you must force-reload the page. OTOH, if you read the page or check the diff, it will probably resolve immediately.
Yep, that will be the case. The problem is not, that it's disturbing me, the problem is, that it's there at all, without any fathomable reason. And it's definitely a bug, it's something I connect with 2017WE, as it was only with this editor that I experienced such stuff. Grüße vom Sänger ♫(Reden) 18:04, 3 February 2017 (UTC)
Yes it is really annoying Bekah Jones