Two registration forms – only one working

I have two registration forms – the only difference being that one has registrants go through a “pending” status first (Let’s call it “form 1”), and the other for pre-approved people to get approved automatically (“form 2”).

They were both working perfectly until recently. I don’t know if this is just coincidental, but we noticed that “form 1” stopped working after I installed Let’s Encrypt. “form 2” still registers users. I have checked all my URLS and all that to make sure all are https://.

By “stopped working” I mean that the user fills out the form, gets a blank page. They are not added to the wordpress user list, nor are any emails being generated (which makes sense since they weren’t added as a user).

I did a little more digging in my Ultimate Member settings. On UM >> Settings >> “Set Up” tab, where I select pages for Log In, Log Out, Profile, etc — the “Registration” line is linked to the form used for Form 2. Would this prevent the other form from being used to register? reminder: they had both been working since December, and this has only been a recent development.

I’m lost and don’t know what to do. Any help would be very appreciated!