I am having trouble with a few links on our site with BB. The behavior is identical to this thread https://community.wpbeaverbuilder.com/t/502-error-when-trying-to-launch-beaver-builder/10777
If BB is disabled on those pages, it works without the BB formatting. If I try to edit the pages with BB I get a viewable page but no ability to edit. If I try to view the page from any link or menu I get a 502 error. I did not see details of the fix in the above link, so I was looking for more info or others that have a similar issue.
The site is using the pro version.