where is garmin/firstbeat hiding lactate threshold pace?

When a new lactate threshold is first detected it appears to be recorded in the special global 140

The heartrate is in local field type 14

But pace is supposed to be in 15, when it's zero. So it's been moved?

I cannot spot another record with meters per second or a link to a another timestamp/event.

Any ideas?

Field 16 seems triggered during LT event but it doesn't seem to translate.

  unknown14 (14-1-UINT16): 163   <<< LTHR
  unknown15 (15-1-UINT16): 0       ???  special recorded but zero?
  unknown16 (16-1-UINT16): 124    ???  not meters per second?