Hi there!
Based on your screenshot, it appears you have the access in order to use those statuses, so it's interesting you're having issues selecting a value. Are you experience the same thing when selecting any of the other statuses or just the Ready for Production status?
Sounds unrelated, but try clearing your cache and try again. Are others experiencing the same thing? If it's just you, it is likely caching. If it's broader, check that the custom form associated with this question is still active. If still active and not working for users, this should be raised with WF Support.
If this helped you, please mark correct to help others : )