I’ve added a new asset type that derives directly from UObject and added a Factory for it, but it doesn’t show up in the Create context menu in the asset panel. Stepping through the code, it turns out that there aren’t any IAssetTypeActions defined for plain UObjects, so the function UAssetToolsImpl::IAssetTypeActions() returns a nullptr, as it cannot find something that has my class as a subclass.
Changing my asset type to derive from e.g. UTexture instead confirms this, since it then appears as it should in the create menu (although in the Materials/Textures submenu, rather than in Miscellaneous). But shouldn’t it be possible to create assets directly derived from UObject in the asset panel as well?
I had this problem in UE 4.22, but recently updated to 4.25, and it is still there.