Custom icons for actions not used in 2019.3.1

I have set up a bunch of custom actions using the Run Configuration As Action plugin. For each one, I went through the Customize Menus and Toolbars dialog and assigned an icon. This worked pretty well in 2018.2, with one catch: every time I ran IDEA in a new project, I'd have to go through the dialog and refresh its knowledge of the icons. An action would show the default icon, but when I go to edit the icon, it still has the path to it, so I just have to hit OK and it then gets it right:

The icons are stored in $HOME/.IntelliJIdea$VERSION/config/options/customizations.xml  (I can see them there), which is how they're remembered, but somehow the UI doesn't know about them that first time. Going through the above process (or the easier process of using the Add Action dialog and scrolling to each one and hitting Set Icon) kicks it in the bytes and tells it to remember them somewhere else that I haven't figured out yet.

For 2018.2, anyway.

I just upgraded to 2019.3.1, and as expected, hit the same problem. But when I went through the above motions to kick the UI, it didn't remember the icons like 2018.2 does. It used them for the duration of my edit session, but when I restarted IDEA, they were all gone again.

Is anyone else using custom icons? Are you seeing the same problem? Got any ideas? Obviously, I can report this as a bug, but I'd love to find a workaround first.