Ok so I imported a modlist from a friend via string, and I see in the description that you can mass install mods that you have in a modlist by clicking on a button below the active mods list. That button is either not there for me, or I am misunderstanding the mod.

same :(

I placed a mod list in the folder and i could load the list to see all the new mods greyed out in the active list.
There is no subscribe button and going back to the main menu or restarting Rimworld removes the greyed out mods.

I've made a patch that might fix the issue: https://github.com/fluffy-mods/ModManager/pull/168