Items attached to the Skeletal Mesh in the World Outliner can alter the Mobility of the Skeletal Mesh.
Licensee specifically does not want to have any automated changes to asset mobility to happen just exposure of the functionality and a build warning to occur.
Also Tested in 4.11 Preview 5 and Dev-Main-CL-2868905
*Quick Repro: Open Attached Project, Open Output Log and PIE*
RESULTS: Mobility Errors and Skeletal Mesh not allowed to move because of the errors
EXPECTED: Mobility of Skeletal Mesh is exposed to allow changing it back or keep the Mesh from Changing Mobility when an attached Actor is Changed.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-27016 in the post.