Plasma6: Dolphin forget sidebar-settings and PDF Icons in Dolphin not shown

Some times Dolphin forget the setting, that i want it to show the sidebar (F9), i dont know why but it is not all the time but sometimes.
Another problem is, that Dolphin not shown anymore preview of PDF-Files.
In the old Dolphin under plasma 5, under Setting - Preview there is a markable point for “PostScript-, PDF- and DVI-Files”. In the new version under plasma6 there is no such thing in settings.

Greetings
Raffinade

Same as

You must be missing the package that provides pdf thumbnails.
Check you have installed:

kdegraphics-thumbnailers

Or you can try the solution:

this is installed, but pdf preview did not work. I also change thing like manjaro, but this has no effect.

I’ve done all the things above, but there is no solution. i reinstalled kdegraphics-thumbnailers but no help and i removed .cache and .share/mime but no luck.
The entry in preview in dolphin “PostScript, PDF and DVI files” isnt shown as the preview of pdf files.

The problem also exists on a fresh neon installation. Just tested in a VM.

That’s a bug in KDE Neon most likely, please report it.

For PDF thumbnails see 472661 – Video and pdf thumbnailers do not work because kdegraphics-thumbnailers doesn't build for Qt 6 yet

For panels disappearing see 481952 – Panels are hidden after minimizing Dolphin window

Oh ok thx, then i have to wait until its fixed

Ty for answering

Greeting

Raffinade