another clipboard misbehavior with libreoffice

[genflux]

Hi,

i use fluxbox (1.3.7-r4) for decades on gentoo/funtoo and no problems. qt-5.15 is used for several programms. So it just lead to try lumina.
It is working quit well - but ! - one thing is really disturbing : no way to copy formulas from one cell to another in libreoffice-calc (6.4.5.2).
ctrl-c is just pickung the value and not the formula. Even copying the formula is not working correctly because it hardcopys the row/col values absolutly. So by inserting the row/col-references are not changed.
What i tried since now :

1. xclipboard
2. copyq
3. not using ctrl-c/v but using the menu. Even inserting just formulas with ctrl-shift-v is not working.

Neither works copying into multiple cells. Normally if you ctrl-c a formula and mark serveral next row/col's, the formula is inserted with changes of row/col-references into each marked cell. Here the value of the copied formula is just inserted into the first of the marked cells. Others left empty.

There are two hints.
Some other desktop environments have or had the same problem. It points to a wrong implementation of X11-API protocols. And this happens inside lumina itself or by lumina using the clipboard-API from QT, because when i start fluxbox (on that same installation) instead of lumina, everything is fine. No problem with copying anything to anywhere.
None of the open or resolved issues i can see here is really connected to this problem or giving a solution for it. Maybe i missed something.

Whatever further infos you need i will deliver.
Thanks in advance
Karl