Problem:
The user is unable to save any WYSIWYG custom field.
Solution:
With the last version 3.4.14, we have an edge case that makes the WYSIWYG fields to be emptied if the post type has the Editor option disabled. Check this screenshot http://prntscr.com/1tqbg8p
As a workaround, we suggested to our user to enable the "Editor" option.