I have already complained about same keyset problem with Sanbox and Production few days ago. The Sandbox keyset disappeared and error message "An unknown issue has occurred. Contact the website administrator" has been popping every time. Then the functionality was restored but today the issue is reproduced again. I'm totally blocked with Ebay integration. I cannot use the ugly Sanbox and I cannot use the Production keyset too due to notifications which are not working. Nobody answer to my and to other developers issues!