Created attachment 167976 [details] test document, simple rectangle two cell anchored The attached test document is just containing a simple rectangle which is two anchored. If you load this document and are vertically flipping the shape then it loses the correct position/size after a save and reload.
I have recently worked on vertical flipped shapes. Please try a daily build to see whether you still see the error. I cannot reproduce the error. A daily build can be installed parallel to your productive version. https://dev-builds.libreoffice.org/daily/master/
Thanks Regina, in the daily developer build everything works at a glance.