Hello Nam,
here is the response I got about K3 support short time ago:
"USB Multilink FX RevA and Universal Rev A and B are based on legacy UF32 USB devices, which are no longer actively supported/validated by PEmicro under the latest plugins/software packages.
To get latest support user would need Multilink FX Rev C, Multilink Universal Rev C/D or Multilink ACP"
Hope this helps.
Regards,
Lukas