Hi,
Hope you guys are doing well. I had the same issue and my problem was the “subsequence” was not working well. I had the MAIN scene on the sequencer. I had two characters that were interacting in that main scene. I created a subsequence of “side” characters. They were 3 in total. None of them rendered their hair.
When I moved those characters from subsequence to the main sequence, everything worked again. I had tried reloading ALL the metahumans that I was using, I had tried checking the files to make sure that the hair materials didn’t get deleted accidentally, but this is what ultimately fixed it for me. Subsequence…at this point, I cannot trust it. I may be using it wrong but I tried everything you guys did above…even the LOD Sync with forcing LOD0/1 and none of that worked until I tried above. Hope it helps you guys and good luck!