Why did vernon j. baker have to wait until 1997 to receive the medal of honor for his actions in world war ii?

The medal of honour is considered to be one of the highest awards a member of the US Army would likely receive due to his or her contributions in the course of a war. In addition,  Vernon J. Baker was among the brave African-American soldiers who fought the second world war to receive it which was delayed for there was a lack of evidence to support his case.

I know the question was already answered but the correct answer for this is D

Just checked on Apex.