A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
This is a very old issue. Back in the days when there was a Macintosh Business Unit (MacBU) they were focused on making Microsoft Office as "Mac-like" as possible, especially when it came to interface design. Someone in MacBU decided that forcing gray button backgrounds is more "Mac-Like" than allowing developers to choose the background color. You can set the color in the VB Editor, and it will display using your setting in Windows, but not on the Mac. I don't like it like this either.
You can post a feature suggestion to have this odd behavior changed back to the original when it used to work. I don't see an existing suggestion about this. If you post a suggestion, please reply here with the link so I can vote for it. Thanks.