When a transaction fails to track or settlement of it between merchant and bank is taking time, reward points won't be given for such transactions for time being.
A debit entry in your account and credit entry for your cc or any product purchase doesn't mean the merchant and bank settlement is completed. Sometimes this txn stcuks to verify and merchant has to wait although a success transaction won't come back but till settlement is done, this txns can't be rewarded with points. Only when it settles at backend, rewards are given automatically.
The things don't run the way a normal user understand at the backend. So others getting and you not means your txn is stucked somewhere between merchant and completion message didn't reached the server. When auot-process fails, banks every month or every 3 months reconcile things manually and then the points come automatically when these txns are reconcilled.
IT system are working in mysterious ways and even best of engineer inside me can never answer as to what leads to such things sometimes. Mostly we blame the connectivity issue or bad packets or corrupt data packets transfer which confuses the system.