yes, there was a mismatch between the two values. The newest MWG version 7.2 (release candidate) that was released yesterday contains already a fix for this. All other that can not or don't want to install this can help themself by adding the ruleset shown below. This will prevent the mismatch if placed at the top in the request cyle.
The release notes can be found once you are logged into the cloud & content security portal at https://contentsecurity.mcafee.com/documentation_mwg7.
7.2 release is pending (within next two weeks).
So does below section of resolved issues, in release notes 7.2, address this bug?
"In responses that contained a VIA header this header was not removed,although a rule set and rule with the Header.RemoveAll event was enabled.(670020)"