I know this post is from a while ago, but I face the same issue. I tried the solution 2 @henrywight suggested, but it doesn’t seem to work properly for my site, nothing changed in the registration form even though I also included the CSS. This is the page I’m referring to: https://starkehand.org/registrieren/
I would appreciate your help very much! Thank you already in advance.
@mercime, unfortunately, that didn’t work, there is no specific layout with or without a sidebar.
@clickallco do you know which file I’d need to put that into? And if I reassign the directory through BuddyPress settings to a different page, the sidebar does appear on the ‘datenschutz’ page, which is why I thought it wasn’t connected to the theme but I could totally be wrong.