well, it could be.
sometime, Vortex seems to not instal mods correctly on the first try, make sure that you have the mod configuration Menu.esp activated in the plugins, right clic on the MCM and MCM bugfix mods to reinstal it and use the 1.5(default) version.
i suggest that you disable all mods, then do a clean MCM reinstal and test it out.
I had a quite similar issue today , MCM enabled, plugin activated,... but no MCM in the game, just reinstalled it 3 times, and it was it.
tell me if it worked.
(don't forget to purges and redeploy and use the archive invalidation)
