I encountered an issue: I imported an Fbx file with morphs to Unreal 5.1, but the morphs of an Fbx file were not fully imported. Some morphs were missing.
But I opened the Fbx file by Blender, and morphs of the Fbx file were fully imported.
It is very wired.
I just experienced this too, same thing happening on 5.2
Could have to do with how the morphs work / what they are associated with / or how they are named.
For instance, the engine has limits to how many bones can affect a single vert.
This could (Doesn’t mean it is) be similar for morph targets.
Personally, I have never experienced this with over 126 morphs on a single mesh, so it is odd.
However my morphs dont usually change areas which are already targets of other morphs…
So, yes, it is a lot of morphs; but, it may not accurately represent the situation you are encontering.
On top of it, it could be a 5.* issue with the importer too.
Best way to check is to import into a 4.* version to see if they show up or not.