Max If Function across several Sheets

Hi All,

I recently came across a function which I cannot make it work.

As per attached file, I will need to retrieve the last contact date in master page after having my function checking all the weeks sheets in my file.

The function I am using is:

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However, it looks like that this works when there are no comments in the weeks sheets while it doesn't work when there are comments.

How can I adjust this function to make it work independently from the presence of comments?

Thank you