Could you tell us the exact reproduction steps?
I could not reproduce the issue with the following steps:
1. Place an empty entity in the level and add a mesh component to it
2. Select the Material from within the entity properties
Result: Same window as you but with another section to the right of the window where the material can be chosen.
Make sure you have updated the CRYENGINE Engine and the SDK as well
To update the GameSDK: CRYENGINE Launcher > Library > My Assets and click on the CRYENGINE GameSDK Update.
To update the Engine: CRYENGINE Launcher > Library > My Engines and click on the CRYENGINE 5.5 Update.