PO field vanished

Hi, there!

Thanks for this plugin. I installed it and checked the box to enable the Purchase Order Number field in the checkout page.

Then, I simulated an order to test it and everything worked fine. The field was there and the PO number was registered in the order received.

However, after this first test, the PO field is not showing anymore. I tried several things (accessing logged in or in a incognito window, reinstalling the plugin…) but nothing worked. The gateway is working fine, just the PO field vanished.

Is there anything I can do to fix this?

Thanks!