Neither loop has a step that will exit the loop when it completes its part of the job.
Use Exit Loop IF [$NewInventoryAmount = 0]
for the inner loop.
And change your Go To Record/Request/page step to be:
Go To Record/Request/Page [next ; exit after last]
Thanks! I had already fixed the "exit after last", but the Exit Loop IF is what I was missing. Fixed my problem. Thanks again!