We have the exact setting for WH1 and WH2, but it wasn't working.
however, I have no idea what setting I've tweaked since I posted this question, but it's working now, so that's considered solved...... for now.

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We are on verion 14 Enterprise, we've just setup multiple warehouse.

Have also setup routes for it as well, we can received stock into the 2nd warehouse, and delivery from the 2nd warehouse.

However, when we confirme a Sales Order for/from the 2nd warehouse, it doesnt' automatically generate a purchase order, even the stock has been setup for Replenish on Order (MTO), eventhough we have setup the rules in MTO for the 2nd warehouse.

What are we missing in settings?

Thank you.