I’ll paste the message that I sent for the ticket you also opened on our Help Desk. We haven’t heard back, so hopefully things are working now.
There are no known conflicts with LD 3, Memberium or the BuddyBoss Platform plugin. In fact, I was just working on a site this morning with all of those and our Toolkit. We would definitely hear about any global issues… both Toolkit and Pro are on thousands of active LearnDash sites.
Do you have screenshots of what’s happening when you try to turn things on? It sounds like you’re going to the Modules page, turning things on, then when you reload the page things haven’t saved? Have a look at the console (View > Developer > Javascript Console in Chrome) to check for errors there; it sounds like a javascript issue if things aren’t saving. Maybe another plugin is outputting bad debug data or creating a conflict.
Are you still experiencing the issue with ONLY the Toolkit, LearnDash, Memberium and BuddyBoss active?