I haven’t had this problem, but I know that distance fields can take ages to render, especially if you change to a new UE version and everything needs to be re-rendered. Do you need to have the distance fields working when you build your scenes? If you don’t need them you can uncheck the “generate mesh distance fields” under the Rendering tab in the project settings.
Also, check the resolution of your mesh distance fields. Most objects don’t need more than 1-4 resolution, and making them larger is a waste of time and resources.