Can't create IK Rig for imported skeletal mesh

An option to choose a rig doesn’t pop up when I create a new IK Rig, so then I try to drag the skeletal mesh into the mesh field in a new empty IK Rig but the field flashes red and won’t accept the mesh.

I export the animation from blender, it works in UE5.3 but just won’t get accepted in an IK Rig. I also exported my main character skeletal mesh from Blender and it’s compatible with manny but because of weird bone transforms I can’t animate on it directly so I’d just like to retarget to my Manny compatible rig in UE.

Anyone knows if I need to check something or set some hidden setting up? This used to not be an issue so I’m stumped. I do have IK Rigging on in Plugins.