Strange error in a workbook macro when a workbook unrelated is opened.

So, I have the following code that show/hide a shape based on a cell value that works. But the problem is that if I open another workbook, unrelated to this one it throws a acccess denied error. Any ideas why?

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I suspect it is because the Me is not fully qualified and relates to the new workbook/worksheet.

Laptop is dead so I can't test the theory.

Me always refers to the object containing the code.

Which line actually causes the error?

This line causes an error:

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The strange thing is that it doesn't always returns an error. After some testing, I figured out that it returns an error only if I open a file with grouped sheets, even if is not related to the shapes workbook.

That sounds like a bug to me.