hit4 stuck to 0 - ACR122U

[Mik3Rizzo]

Scenario

Tag: NPX Mifare Classic 1k, ISO14443A
Reader: ACR122U
Host: Raspberry Pi4, libnfc 1.8.0, mfcuk 0.3.8

Problem

Running sudo mfcuk -v 3 -C -R 0:A -w 6, the hit4 counter is stuck to 0 after 3+ hours of computation.

-----------------------------------------------------
Let me entertain you!
    uid: 63fb0244
   type: 08
    key: 000000000000
  block: 03
diff Nt: 331
   hit4: 0
  auths: 62876
-----------------------------------------------------

I got the same problem on other hosts, like a RPi2 and a Linux (Debian) PC with the same software.

I've two other tags, same type, same manifacturer, same host, same command. I got the key in less than 60 seconds. In these cases, the hit4 counter goes along the auths counter (i.e. 180 hit4, 180 auths).

[KPerlman]

Did you ever find a solution?

[Mik3Rizzo]

@KPerlman Unfortunately not, even running mfcuk for 40+ hours.

I've done some researches; probably the tag is a Mifare Plus acting as a Mifare Classic 1k.
The Mifare Plus is not vulnerable to mfcuk.