Question about confusing volatility issue

I'm trying to improve the performance of my workbooks. I'm doing some testing on volatility on 1 sheet at the moment.
I'm using XL2002.
I have Application.Calculation set to Manual.
I have all the worksheets in all the workbooks .EnableCalculate=False except 1 worksheet that I'm testing.

I have 4 workbooks open.
In workbook #1 on the worksheet I'm testing I have a cell that points to a cell in workbooks #2 and a cell that points to a cell in workbook #3 The formulas are:

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Both MtgKey cells do not have formulas in them.

I save Workbook #4 and then run this macro inside Workbook #4 to time how long the sheet takes to calculate:

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At that point 1 of the 2 cells recalculates, but not the other.
I then run the macro again and neither cell recalculates.

After saving Workbook #4 there are several cells that recalculate the 1st time I run the macro, but don't recalculate the 2nd time I run it. They all have formulas that have links to other workbooks, so I'm assuming that has something to do with why they recalculate after saving any workbook.

But why don't both of those cells recalculate?

Thanks;
I've read that a few times, but I decided to read it again and I saw something that I think explains my confusion.

I never noticed that workbooks get flagged as Dirty. So even though the MtgKey cells themselves weren't Dirty, one of the workbooks was, so that cell got recalculated after saving any workbook.

That explains a few inconsistencies I've noticed.