Windows Server 2016 - Setting up a file share. Permissions work with individual users, but not groups?
However, I also, under the account I am using, belong to the Domain Admins group
Your answer is 'UAC'. The 'UAC' filters out the 'Administrator'/Domain Administrator' privileges from account for most processes.
I bet if you used a different group everything would work as you expect.
I suspect you are also attempting to test these permissions locally from the server. If you were testing remotely you would also not have problems with the UAC, since the UAC filtering only applies locally.