Are you still using the tool as a global installed tool? From your previous reply
If this is the case, I will need to reiterate that the tool should not longer be installed as a global tool. I’ll link again to my post detailing this information here
For the MGCB Editor to function properly, you’ll need to include all of the tools that are outlined in that dotnet-tools.json file that I have in that post. Specifically the dotnet-mgcb tool is the one that contains the libmojoshader_64.dll
I would highly recommend that you do not use this as a global tool and instead keep it as a local tool. Setting this up as a local tool is explained in the post I linked above.