Hi @friech,
I deactivated everything but cornerstone and Slider Revolution, and the problem still shows. However, to make absolute sure, I created a new temporary domain on my host and installed X, Cornerstone and Slider Rev in there on a brand new Wordpress site, changing for a brief moment one of my licenses, and it works fine in there. I’m starting to think that maybe there is some kind of corruption on Slider Revolution when you update it from the previous versions (5.X) to the one with the whole layout makeover (6.X), as it didn’t happen on only one of my sites, but multiple, and they’re all quite different from each other.
Another interesting I checked: on my plugins list, there is a strange little “line” right under Slider Revolution’s title, which, checking on Chrome’s elements inspector, is a message of update, except it’s blank:

Also, on Chrome’s console, the following error shows up on pages with a slider:
Uncaught TypeError: Cannot read property 'getElementsByTagName' of undefined
at c (VM241 rs6.min.js:37)
at HTMLUnknownElement.<anonymous> (VM241 rs6.min.js:37)
at Function.each (jquery.js?ver=1.12.4-wp:2)
at a.fn.init.each (jquery.js?ver=1.12.4-wp:2)
at a.fn.init.revolution (VM241 rs6.min.js:37)
at HTMLDocument.<anonymous> ((index):331)
at i (jquery.js?ver=1.12.4-wp:2)
at Object.fireWith [as resolveWith] (jquery.js?ver=1.12.4-wp:2)
at Function.ready (jquery.js?ver=1.12.4-wp:2)
at HTMLDocument.J (jquery.js?ver=1.12.4-wp:2)
I suppose my best option would be to export all my sliders to my computer, delete the plugin and try installing it brand new from a .zip file.