Directory & Super-Smush Not Working On MultiSite Install

Hey guys,

I've been trying to Smush the contents of and images folder in my theme on a multisite install but I'm getting the following error every time I try to do it:

Uncaught TypeError: Cannot read property 'ids' of undefined
at Object.success (wp-smushit-admin.js?ver=2.6.1:1907)
at i (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils&ver=4.7.3:2)
at Object.fireWith [as resolveWith] (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils&ver=4.7.3:2)
at y (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils&ver=4.7.3:4)
at XMLHttpRequest.c (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,jquery-ui-core,utils&ver=4.7.3:4)

I've tried disabling Hummingbird in case it was any sort of issue with any scripts being deferred but no change.

I'm also getting no response from the Enable buttons for Super Smush and resize savings settings, with no console errors.

Wordpress and all WPMUDEV Plugins fully up to date.

Thanks