My offer availability has been fluctuating during different periods of time as well, Alessio. Please just keep in mind that the issue with the button might be just a bug with the button that doesn't let it return to default state so you can try again or goes gray because there are no videos available atm. While the number of videos you get on all your accounts could be just a matter relating to Offer Availability. :/

This is my own 2 cents on the matter at least. Not sure if the limited amount of videos you gets is related to the button bugging out, basically.