i had simular issues when i tested out the tempery tool control for the table saw.
i initually had 5 sec reads with 2 failed reads, shut the tool down.
in the end i was reading the token every second and killing tool access after 10 consecutive read failures using a countdown register. in operation i was routinly seeing single and double read failures. and occasionally getting 5 consecutive read failures between successful reads.
i use pn532 nfc readers, so your milage would may be different