Custom CSS didn't work on Multisite until I toggled off then on

On a Network/Multisite, I could only get this to work when I used the toggle switch at the top of the settings page to toggle off then on.

Yesterday I installed this on a Network/Multisite. I network activated it. I then went into each sub-site to add Custom CSS, then Save Design Settings. The CSS didn’t apply. Eventually I figured out that by just going back into the settings, and using the toggle switch at the top of the settings page to toggle off then on, caused the CSS to apply. I didn’t even need to Save Design Settings a second time; just the toggle was enough.

It would be nice if this extra step wasn’t necessary; it took me a while to figure it out.

https://wordpress.org/plugins/custom-login/