excel stepping into UDFs when changing links

I have the following macro

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which if I do manually through edit links works fine but when I run it as a macro and F8 through it it gets to "ActiveWorkbook.ChangeLink vLink, ThisWorkbook.Name, xlExcelLinks" and then tries to run through the addins UDFs but with no values and it crashes out.
e.g. one of my UDFs is

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and it will start stepping through this with the input variables being location = error 2015 & mass = 2023

what is excel trying to do?

If I expand the variables in locals it looks as if excel upon changing the link in the first cell tries to recalculate it however it hasn't yet updated the links in the second cell (which is an input in the first cell) and falls over.

does the link change go through 1 cell at a time and trigger calc manual on each cell change? but then you does this not fall over when using the edit ribbon edit links button (as it is the UDF that is falling over from this)? is there a way to totally disable calculations temporarily to get around this?

Is there a way to do it without using

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?

isn't using On Error in itself not coding properly? as you are not using an if then statement to prevent an error you are just dealling with an error if one arrises.