Hi PNgan,
Please try and create a new SharePoint list and see if the same behavior happens.
We'd also like to confirm:
- Whether you are using modern experience or classic experience.
- What customization has been done on the list.
We created a new list and can see the Save and Cancelbutton. There is a possibility that you have entered Quick Edit view, so would like to get a screenshot of how it looks on your end.
Regards,
Sheen