Hi there, the fix for this issue would be to retrigger the subscription so our system has a new notification telling it you have Multiplayer permission.
Recurring Billing Fix
A user-side fix that has worked for several users would be cancelling recurring billing, and then turning it back on after a few minutes. This should send a new notification out to our system that you have Gold (which should "fix" your account and Home Console). After this fix, turning off/on the console may be needed to.
Billing Team Support/Xbox Support
Alternatively, you may contact the billing team regarding this issue, stating you have an active subscription but aren't receiving the benefit. They should be able to cancel your subscription and restore it, which should also effectively "fix" your account and Home Console.