None Option is Added by the System in a Custom Field

[syee]

I'm getting an option None in a multiple choice custom field, when I only added two options as part of the context. I've been looking for possible solutions in the community and already did everything people proposed, setting the field as required, set a default value.. But I still see the none option as part of the multiple choice field and it doesn't allow users to continue with the transition of the ticket even if they have selected None as an option.

Is there something else I can do in order to get rid of this None option?

Also as you can see in the next image, when someone selects None and clicks on Completed, the options are being duplicated with no reason.

Here's an example of another Multiple Choice custom field, that is required and the system is not adding this None option as part of the list.

[Sarah Wright]

Is this the list of tried suggestions for workarounds from the documentation? 

https://confluence.atlassian.com/jirakb/remove-the-none-option-from-a-select-list-custom-field-in-jira-server-144212308.html