Whilst I cannot vouch for any windows installs, I can confirm the background dash colour is selectable on both my self built RPi server and my emonPi. Both are up to date.
Yes, you are right, it’s a windows server too. One is IIS and one is Apache and on none of them it is working. So you are able to change and store the dashboard colors? Interesting…
Yes, I have never been aware of a problem with saving dash backgrounds and I do use it fairly frequently, but only on Linux/Apache (on Pi’s), I colour code dashboards for easier recognition when I have several windows open.