[v6 General Discussion] Primary window and foldback out of sync

We are using EW6 for quit some time. We use the foldback option to create a smaller window that can be used for a television broadcast. Recently we encountered a strange problem: the verses on the primary window and on the foldback are out of sync. That means that on going to the next verse of a song (verse 2), verse 1 remained on the foldback. When going to verse 3, verse 2 was showing. Going back to verse 1 showed verse 1 on both screen.

Any idea what may cause this behaviour?

Are you able to replicate it? If you close and re-open does it do it every time?
It usually happens when I am not around

Does not seem to happen all the time.
That is what makes it hard to pinpoint or troubeshoot this issue.

Restarting EW6 seems to do the trick when we see it happening before the service starts.
But that is not an option when the service is in progress.