PN532 not responding using SPI when issuing antenna-related command
In my code that communicates with the PN5321A, the inListPassiveTarget function has a time-out in case there is no NFC tag present. I set up an IRQ when I call inAutoPoll and do not wait for any more response after the ACK frame. Are you certain that your hardware is working correctly? The operation you describe is normal for no tag present.

I observed the RF output of my antenna on my oscilloscope with a 15cm loop of wire clipped to the tip of my scope probe and connected to the GND of my scope probe. I put the loop around my NFC antenna and NFC tag (all flat on my desk). I could see the load modulation of the response from my NFC tag when the RF level rises slightly. The bits where the RF signal disappears is when the host is communicating with the target.