When Oxygen is activated I can’t change Custom fields

Hi!

First of all thank you for the great work with this plugin.

Now to my issue:

When I have the Oxygen plugin activated I can’t change settings for Custom fields. I want to be able to add _sku into the “Custom fields” field. But every time I do that or change to none, all or visible and hit “Save the options” it reverts back to the setting “some” and fill out the field with ct_builder_shortcodes.

How can I fix this?

The page I need help with: [log in to see the link]