Hello @b-honderd I am sorry to hear you have expereinced a black screen after you claimed rewards and tried to navigate the menu and activities.
In order to try and resolve this issue or narrow down a few possible things that may be causing it, could you please follow each step you have yet to try in our tech troubleshooting guide? This guide contains the most common fixes for issues caused by Windows permissions, hardware, software and out of date drivers >
https://www.ubisoft.com/help?article=000061047
Should the issue not be resolved after performing the steps above, are you able to record a clip of what you press in the menu to show us exactly when the game crashes?
To send us a clip of this happening in-game please use the Windows, Alt and R key, to start recording a clip with Xbox Game bar (Usually comes already installed on Windows 10&11) and post this clip to a hosting website such as YouTube or Imgur for us to be able to view.