Using Joomla 3.7.4 with PHP 7.0, updated to MSocial 3.21.3 though the extension manager, then manually via FTP but the template settings are not loading in either case as described in the beginning of this thread.
I am not sure if I had the problem on Joomla 3.7.3 ...
Thanks. The code in scripts.js was already accurate so the problem is probably not coming from there. Today I managed to get the tabs appearing again but only in IE10. On Chrome (Windows + MacOS Sierra), Firefox (MacOS Sierra) they don't appear. Cleared cache to make sure but nothing helps.
Just checked Chrome with old and new Joomla version, with the fix and without. I can confirm the fix works despite of the browser, so I'm guessing the browser's cache was not cleared fully.
Also this is the only report of the /admin/scripts.js modification not brining results, so please also check some 3rd party plugins for joomla and browser which may be affecting javascript.