I had an account tenure of 7 before my membership expired and my account went Silver. I just renewed my Gold with a 12 month a few days ago and the tenure has not updated.
My tenure is blank on my profile, I believe it should be 8, maybe 7 still I am unsure.
I tried the recommended fix of deleted my profile, then I turned off my Xbox, woke up 8 hours later and downloaded my profile. The fix did not work.