SQL 2014 - Group Membership for sysadmin permissions not working

Question

I am using SQL 2014 on Windows Server 2012 R2 and am running into a permission issue. During the install I specified the local server's Administrators group as well as my specific domain account to have sysadmin privileges. 
The issue is that accounts that are a member of the local server's administrators group can't even login to SQL Server Management Studio unless they are specifically granted permissions for their account (my domain account works fine as it has a specific
credential in SQL).
The log just gives the following error:
Login failed for user 'domainname\username'. Reason: Token-based server access validation failed with an infrastructure error. Check for previous errors. [CLIENT: <local machine>]
Error: 18456, Severity: 14, State: 11.
I haven't had this issue in previous versions. Is there something that must be done differently in 2014 to grant permissions to groups?

Answer 1

Hi, something like
this?
Bye
Questo post è fornito "così com'è". Non conferisce garanzie o diritti di alcun tipo. Ricorda di usare la funzione "segna come risposta" per i post che ti hanno aiutato a risolvere il problema e "deseleziona come risposta"
quando le risposte segnate non sono effettivamente utili. Questo è particolarmente utile per altri utenti che leggono il thread, alla ricerca di soluzioni a problemi similari. ENG: This posting is provided "AS IS" with no warranties, and confers
no rights. Please remember to click "Mark as Answer" on the post that helps you, and to click "Unmark as Answer" if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.