When I turn on my PC KDE Plasma 5 panel isn't transparent - I have enabled Compostitor, but my panel and the others widgets have solid background without transparency. Other desktop effects works without problems. I can fix this problem always with the command kwin_x11 --replace. After this command, the transparency in the Desktop theme returns as must be after the user login. 

Reproducible: Always

Steps to Reproduce:
1. Turn on pc
2. Login the user in Plasma session
3. There is not transparency in the Desktop theme. Neither Panel or widgets, only a color solid. 
4. The compositor are initialised because the other effects work fine.
5. Run kwin_x11 --replace on Krunner (or console)
6. Transparency in panel returns.

Actual Results:  
There is not transparency in desktop theme every time that turn on my pc.
The transparency return always when I run the command kwin_x11 --replace.

Expected Results:  
I expect transparency immediately start the desktop session, without reinitialise the compositor or restarts kwin.