Try reducing the element size. You can also try the alternate mesher, which is especially good if you have lots of curves in the part. Is the part hollow or thin walled? If so, you can try setting it up as a shell mesh.
I know this is an old post but I had a similar issue recently. I have no idea why but deleting the study and starting from scratch looks like it works. It seems like the fixtures and loads are added to a hidden body for some reason even though they are obviously on the included, visible body.