I use the same appearance in all of my models. I have about two dozen material appearances I've created.
I went to apply one of them in a newly created model, and they are all gone.
I went into an old design, and the custom appearances are still applied to the parts, but also did not show up in My Appearances. So it's not an issue with an individual model.
I'm able to go into old models and re-save the appearances into My Appearances using Right Click > Copy to My Appearances. But this is a workaround. It'd be great to get them all back.
