This is a regression tested in //UE4/Release-4.27 CL#18319896
GPU Lightmass ignores IES Profiles on Static Lights while building lighting. Tested with different Global Illumination and Reflection settings all resulted in incorrect lighting except Lumen which doesn't support Static lights. DumpGPU included in comments.
Lighting builds and the IES Profile is visible
Lighting Builds and the light doesn't appear to have an IES profile regardless of Global Illumination/Reflection settings.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-156122 in the post.