I remember changing this from ZoneSense to HR some time after ZoneSense was introduced.
You can change it in the activity under Edit, and I assume that setting then becomes the default for later runs as well.
What I noticed is this:
NGP appears with TSS ( r), TSS (hr), and TSS (p)
NGP does not appear with TSS (ZoneSense)
Also, the calculated TSS differs quite a lot for the exact same run:
TSS (hr): 105
TSS (ZoneSense): 86
TSS ( r): 53
TSS (p): 109
To keep my data comparable with older runs, I switched back to TSS (hr), which I think used to be the default.
Is there a logical reason why NGP is not calculated or shown when TSS (ZoneSense) is selected?