Other Specialized TCD display how to resync HR monitor?

[Mtbvkk]

I noticed the other day that with the HR monitor synced which happens automatically when I turn on the TCD, if I walked out of range and came back it wouldnt resync the HR monitor. Is there a way to force it to resync? In general i really like the TCD for informational purposes and can even ride stealth with a top tube bag over the TCU.