I was experiencing this myself recently when trying to run DynDOLOD through Wine/Proton. After a few days of confusion, it appears to be this Wine bug that causes Texconv to fail if -nowic isn't supplied as an argument. This Wine bug has been fixed since Wine 9.0-rc2, and I was able to successfully generate DynDOLOD after upgrading to Wine 9.0 (in my case, I installed the full 9.0 release).
Hope this helps.