There is a big bug with the latest version of RW (since 8.1) and EASY CMS.
The pages work properly, but as soon as you make a change in the page, the message "Unable to load CMS preview libraries. Try adding a CMS Text stack to the bottom of your page.” appears.
So, i did the following test.
I modified the page, then I removed all stacks except “CMS Core” … And I still have the same error message.
So it seems that this does not come from a conflict with another stack, but with RW.
I then tested with RW 8.0.3 and the problem disappears completely.
Is this problem known? Does anyone have a solution?