I love the bulk network creation tool. After a bit of training for the project manager, he was able to create spreadsheets that I could (almost) drop in.
I assume you have a good reason for staging the APs. In some large deployments, I haven't even taken the APs out of the box before they got to the final site location. The warehouse learned how to scan the AP serial numbers from the side of the box and send them over. The only extra work was taking a sharpie and writing a big #1, #2, etc. on the box and noting that value with the serial number. At installation time, they noted which AP was placed in each location.
If you don't stage the APs, the bulk creation tool works great.
For your issue, have you tried removing the APs from your test network and then unclaiming the APs in dashboard? Make sure you wait a little while, as you won't be able to immediately reclaim (through the bulk creation tool). I've never seen an exact time, but in my experience, it's longer than a cup of coffee, but shorter than lunch 🙂