How Do I set up a Precision Time Protocol (PTP) client for PTPv2 Messages from Smart Switch on Windows 11?

Question

I have a simple air-gapped system which, for the sake of this question, consists of a Windows 11 system and a Smart Switch (NSW-12) capable of serving as a Precision Time Protocol (PTP) grandmaster clock. Currently, the switch is set to serve PTPv2 messages to this Windows 11 system. I have verified that the PTP messages are arriving. They are doing so in a multicast message, e.g. 224.0.1.129:319/320.
I followed the steps here https://github.com/microsoft/W32Time?tab=readme-ov-file using my switch's IP address in the PtpMasters registry, but I am starting to think that the multicast is where I made the mistake of thinking this works. In the event viewer, the system was unable to lock to the grandmaster with EVENT ID 516 "Messages from PTP Master will be ignored because the master is not allowed". I also tried w32tm /resync, which failed.

Is it possible to configure the Windows 11 system to accept these multicast messages with W32tm, or does this require a dedicated home-grown service? Our requirements are to use the time from the PTP messages as the time source. Millisecond precision is our goal, and the NSW-12 is only a single jump from our system; the documentation I read suggests this is possible.
Finally, is the system clock the preferred method to read this time, or should I look at dissecting the PTP messages myself?