Nope, “use with morph target” was already ticked.
The problem actually affects the WHOLE level, ALL assets lose their shaders.
Buuuuut - i found the problem. Imho a BUG. 4.17.1 here…
I had used a skeletal mesh and applied the morphs. Then the problem occurs. When i use an Animation sequence it works as expected. So NEVER apply morphs on the mesh, apply them to an animation sequence, even if you don’t plan to animate the mesh.
I say it’s a bug because if SetMorphTarget isn’t supposed to work with skeletal meshes it should throw an error, NOT crash all shaders.
Edit: Interstingly “SetMaterial” (Rendering) has the same bug, just vice versa. So if you use SetMaterial on the Animation Sequence it will also kill all shaders…
Edit: OK no bug, but silly problem…
For debugging purposes i had put the functions on “random” keys. So F2, F3, F4…
While you CAN use the F-Keys and they do run the functions they also seem to have some engine specific stuff, like F4 turns off shaders or so…
Have put the functions on other keys and all weird behaviour disappeared. Oh well, lesson learned i guess…