Some customers have found video games on Amazon are now "exclusively for Prime Members".
Customers are clicking through to buy items in both the UK and US and finding certain titles to only be available for those who pay for Amazon's Prime service.
Customers around the world are also reporting other titles being restricted, including Tom Clancy's Rainbow Six Seige, Assassin's Creed Syndicate, Far Cry Primal, Battlefield Hardline, Dishonored: Definitive Edition, Metal Gear Solid: Ground Zeroes and Farming Simulator.
Amazon hasn't announced the initiative, but the "exclusively for Prime Members" logo has been around since at least April last year. Previously items as diverse as movies and even nappies have been affected.
The exclusivity does not appear to apply worldwide. While the US version of GTA 5 is locked, the UK listing for GTA 5 on PS4 appears to be available for purchase by anyone. Meanwhile the Xbox one version of the game is unlocked across both US and UK.
It's not yet clear whether this initiative is meant as a means of dealing with low stock levels or whether it's simply meant as an extra reason to sign up for Prime.
However, the seemingly random exclusivity of titles across platforms and regions suggests that these titles have not been specifically chosen, indicating it may be an automatic measure to ensure stock is available for Prime customers.
Thankfully you'll still be able to buy affected titles if you are on one of Prime's free 30-day trials.
When asked for comment an Amazon spokesperson said "From time to time, Amazon offers exclusive selection and pricing on select items, including select video games, for Prime members. Customers who are not Prime members can sign-up for a 30-day free trial of Amazon Prime to benefit from these exclusive prices and 30-minutes early access to select Lightning Deals, or they can purchase these items or similar products from third party sellers often fulfilled and delivered by Amazon."