Dear community please help?

Our web designer, well is no longer a web designer, and before she left we hosted the site on WP engine. Now our new web person cant do any design on the site - and tells me that its down to Beaver Builder - not letting him, and when he tries to add a full width building block he gets the following error. "Beaver builder caught the following java script error… Cannot read properties of null (Reading multiple on line 1… (as per below)

Can someone please help or advise me on how I might get this resolved?

I didn’t even know that Beaver Builder was being used - on our site tbh?