Unable to effect Exclude in element - metabox.js Error

Hi,

Recently I've found I'm unable to access the 'Exclude' setting in the Elements. When I go in to any element 'display rules' I'm seeing a loading animation. Please see video for clarity https://nimb.ws/DXq2iA

I am seeing the below error in the console. Seems to be to do with gp-premium/elements/assets/admin/metabox.js. Also I have migrated this website to a test subdomain and the issue has not traveled with the migration (rules out plugin conflict?) so it's specific to this install. At a bit of a loss so reaching out in the hopes you might say! Ah, yes its...

metabox.js:170 Uncaught TypeError: Cannot read property 'unshift' of undefined
at Object.success (metabox.js:170)
at c (load-scripts.php?c=1&load[chunk_0]=jquery-core,jquery-migrate,utils,underscore,moxiejs,plupload,wp-codemirror&ver=5.7.1:2)
at Object.fireWith [as resolveWith] (load-scripts.php?c=1&load[chunk_0]=jquery-core,jquery-migrate,utils,underscore,moxiejs,plupload,wp-codemirror&ver=5.7.1:2)
at l (load-scripts.php?c=1&load[chunk_0]=jquery-core,jquery-migrate,utils,underscore,moxiejs,plupload,wp-codemirror&ver=5.7.1:2)
at XMLHttpRequest.<anonymous> (load-scripts.php?c=1&load[chunk_0]=jquery-core,jquery-migrate,utils,underscore,moxiejs,plupload,wp-codemirror&ver=5.7.1:2)