Users editing custom post types with ACF WYSIWYG’s on the screen are always defaulting to the “Text” tab. Changing to another tab does not seem to save as the default. This is a recent problem that seems to only be limited to users within a new user role we created that has the following capabilities:
What editor is shown is determined by the last action a user takes in a wysiwyg field, any field. WP, not ACF stores a value on the last selection, visual or text and the next time the editor is loaded all of the wysiwyg fields will be set to this tab.
I do not know how or where this value is stored by WP, but you can see it in action on an user where it is working correctly. Open any post, change the mode of any wysiwyg editor, wait a second or 2 and reload the page, all editors should not be in the last mode selected.