Hi Kyle,
When using Movable lighting from a Directional light the Cascaded Shadow Maps will reduce quality at further distances to help with performance. You can adjust some of the settings in the Directional Light’s Detail’s panel under Cascaded Shadow Maps to help improve this.
The Wiki guide here can help go over some of the settings: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums
Additionally, you may find that you want more cascades to spread the shadow maps over so you can use the console command r.Shadow.CSM.MaxCascades 10 to increase this to the max count. Then you can set the number of cascades in the directional light to 10. At this point use the Distance and the Distribution Exponent to adjust how the quality is spread across the cascades.
Mesh Distance Fields. If you’re enabled these make sure that it’s been set properly in the Directional Light as well. The option for RayTraced Distance Field Shadows must be enabled. Use a lower setting for the Dynamic Shadow Distance under Cascaded Shadow Maps section so that you can get more quality over a lower distance for CSM shadowing. Distance Fields use a generated mesh for shadows beyond this CSM distance. If the shadowing from Mesh Distance Fields does not look correct you need to make sure that you have enough resolution on the mesh by using Show > Visualize > Mesh Distance Fields. If the quality is not there you can use the documentation here for more information.
The static mesh does not have to be set to Movable to use dynamic lighting for Mesh Distance Fields or with CSM shadowing. It is fine to leave it set to Static. This just sets its mobility, not the type of lighting it uses. In case there was any confusion about that.
I hope this helps get your started.
Tim