Strange. I’m using UE 4.18.2 and Prefab 1.0.7
I double checked my repro steps and still get the same result. (regarding renaming the source static mesh.)
The only thing I can think of is that if one were to do this to a static mesh which is referenced by other assets such that it creates a redirector - I imagine the repro steps wouldn’t produce the same bug since the prefab would point to the newly created redirector. In my case, no redirector for the source mesh is created since no other assets reference it. Hope this helps.
I walked through it a little and have found that the PrefabContent string contains the old source mesh name after the rename.
The prefab which is already placed in level during rename is handled properly but changes to it aren’t propagated to the asset - if I hit apply on the already placed prefab after source mesh rename placing prefab of that type works after. In summary, renaming source mesh fixes references in prefab instances already placed in level but not the asset version of it in the content browser.
I think I found the problem and it has to do with not saving the level during any of the steps. If I save the level even just after placing the original static mesh, before creating the prefab everything works ok. I stumbled on it by looking at where it was getting the content string and it appeared to be looking through the level for the static mesh actor archetype definition which still had the old mesh name. So I suppose I stumbled into an edge case - I don’t imagine this would come up often.