I haven’t experienced this, but it sounds like something the latest update to the PMS GTN is addressing:
Adding a delay between 2 mouse clicks (console only). This is to avoid a sim issue on Xbox where, with the Xbox controller in cursor mode, clicking a button triggers 2 mouseup events.
It’ll be interesting to see how often the marketplace PMS GTN gets updated, considering how the marketplace submission process doesn’t seem like the smoothest of operations.
Edit: as a workaround, you could connect a mouse, if you have one, and enter the code using that instead.