The result of a completed offer to obtain free Robux gets finalized by the offer service provider. A reliable reason for offer not getting credited would be due to providing repetitive information, ad-blocker causing unwanted tracking problems or the offer is itself bugged. Usually, it takes a few hours to credit the values of completing an offer.
Unfortunately, we do not have the power to honor the credit completions, and only the offer service provider gets to decide if it has been completed or not. If you are cent percent sure that the offer has been correctly completed and yet to receive updates in the past twenty-four hours, then you can contact the respective company for offer assistance. If you are facing errors while trying to complete desktop offers, then switch over to the mobile device and find rightful sources to complete the offer.