PMS not working on QNAP TS-451 but works perfectly fine on QNAP TS-253

PMS working or not is completely independent of the PlexData share (which is for diagnostics and maintenance only)

The referenced thread highlights the inconsistencies seen due to QTS firmware differences.
I can’t explain why this is so.

I suggest reading that which has transpired since the referenced post rather than the singular complaint about having the functionality.

May I also highlight the QNAP FAQ which now documents the feature.