XF 1.5 approved posts from moderation do not show up

[high1976]

We have an issue with to be moderated posts since some days/maybe weeks (latest XF-version, PHP 7.0.17-1). The approved posts do not show up in threadview and can not be reached by direct link. Only way to get them visible is to 'Rebuild Thread Information' (always used Rebuild position and post counters too but not sure if it's necessary) from AdminCP.
Any idea what might be going wrong here?

 

[Mike]

This isn't something that I've ever heard of before. It sounds like the position is somehow calculated incorrectly if rebuilding the positions fixes it. An add-on interfering is the only thing I could think of, so it's worth confirming the issues with all add-ons disabled.