Cinnamon bug?

I don't know if anyone will have an answer for this, let alone come across this issue.

I run Cinnamon on Ubuntu 18.04, and for the most part it works well. But there is one notable exception. I have a number of launcher applets on my panel. If I have just booted up then I can re-arrange their order by moving one applet to the left or right, with the other applets making space to accommodate the new position. But if I try to repeat this procedure, say move another applet, most of the time it will not move, or eg, if I try to move it to the left by one position sometimes it moves by 2 or more positions, if it moves at all. If I logout and login again then it will work fine first time I want to re-position an applet, but after that it's the same issue again.

Any ideas or help would be appreciated.

Which version of Cinnamon? I cannot reproduce this on Cinnamon 3.8.8 (on Debian 10, rather than Ubuntu).

It's Cinnamon 4.0.9. I should point out that if I use Ubuntu 16.04, that has Cinnamon 3.6.7 it causes no such issue.

Looks like it could be an issue with that version: https://github.com/linuxmint/Cinnamon/issues/8299

So it is a bug. I'm surprised there hasn't been more written about this. Guess I'll have to find an earlier version. Thnx for the help.