Ok, so strangely enough this has something to do with the data in this field. Once this date is changed then for some reason the date selector displays 100% fine. I migrated from version 1.12 to 1.14.2 and then implemented OSTicket Awesome. So obviously something to do with the previous data in the date fields then caused this issue. Once that data is overwritten with new data its fine. No idea how the data in the field managed to cause the date selector to display different but clearly somehow it did.
So this is resolved, and wasn’t actually an issue