Yes it’s not your theme. I’m putting updates here if you don’t mind if someone else has the same question.
Thanks for contacting us about Memberships! Sorry to hear our plugin is giving you trouble. I am happy to help out 🙂
We have received several reports of this issue and our developers are already started looking into a fix here. It looks like the conflict has to do with the latest version of WordPress that was just released in the last day or so.
While I don’t have an estimated time for resolution right now, please know that our team is now aware of the issue and will work to incorporate a fix into the plugin as soon as they can.
In the meantime, though it’s not ideal, I’d recommend looking into using our restriction shortcodes: