I’ve only just switched from Maya to Blender a year ago, but we started using Blender and UE4 just 2 months ago for our projects. It took us a whole month to figure out the pipeline from Blender to UE4. In other words. you rigs and meshes should be very very clean and simple for it to work properly in UE4.
Maybe if you can share your blender rig set up, I could help troubleshoot.