I've tried restarting campaigns, using less mods, and even using only one mod at a time to try and figure out if any of them work or if certain other mods are not compatible.But no luck. Upon startup the mods show up in my list of playable mods, but when I select them they don't appear in the game. I select subscribe, and then I add the items to my collection, and as far as I know these are the only steps required? There is no option in steam to download the actual files and move them places, so I'm kind of confused there because I'm unfamiliar with it. X-Com 2 seems to be a completely different beast though, and I can't get any mods working using the steam workshop.
Although, admittedly I'm not the smartest tech person and I considered myself lucky that I was able to figure out how to install the old school long war mods on my Mac. I'm a supporter of Longwarstudios through and through. It's amazing, it's killed many soldiers of mine and I've successfully fought many battles using the mod and I can't get enough of it. Firstly, I just want to mention that I absolutely love the long war for enemy unknown/within.