This is very weird. I think the copper coins are disappearing! Look at the screenshot: 0 coins!
I was not paying attention beforehand; but some time after I set the Axe production, I noticed the copper coins went down to 0.
Each Shack produces 93 copper coins -- that's an odd number. The settlement started with 3000 or 4000 copper coins I can't remember clearly.
No way the total number of remaining copper coins can be integral multiples of 1,000!
I apologize that I'm feeling super tired so I don't have the energy to report it as a bug (and first of all check all those qualifications for bug reporting, and provide all the background information)
So I just put a screenshot here, let it go, and continue building the settlement. The digging for the bottom is too exhausting.
Plus, the settlement does not have a "Pause" button. While I'm doing this, settlement activities are procrastinating...
I think the number of remaining copper coins absolutely cannot end up being zero!
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Update: I think coins have been returned after a browser refresh. I actually have a little less than 1,000.