Mac AppStore Apple submission failed due to "Your application still accesses the following location"

Our Mac AppStore App failed submission for the following reason. Note that we have already sucessfully submitted other Mac apps, so we know about code signign and other requirements and I think we have done that correctly.
This is an urgent matter, please help ASAP! I fear it can only be fixed by Unity. We are building with Unity 5.6.4p4.
Thanks! Michael / ClockStone

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Guideline 2.4.5(i) - Performance

Your application still accesses the following location(s):

'~/.config/.mono/certs/CA’

The majority of developers encountering this issue are opening files in Read/Write mode instead of Read-Only mode, in which case it should be changed to Read-Only.

Other common reasons for this issue include:

- creating or writing files in the above location(s), which are not valid locations for files to be written as stated in documentation.

- writing to the above location(s) without using a valid app-id as a container for the written files.

 

Yikes! That does look like a Unity thing. I hope you get a quick resolution on this.