builder tool not working

dear sir / madam ,

upon trying to edit one of my sites on my wordpress multisite install, the builder [ beaver builder] does not load , with no icon [ BB ] to select across the top bar ... seems to work on my other sites / installs , so i am assuming its a 'permissions' issue ...?

I have done the usual activate/deactivate of all plug-ins and themes , to no avail ....

any help would be much appreciated ...