Anyone else have a Doppler that picks up the heartbeat but doesn’t display the rate?

C

I finally think I found the baby’s heartbeat a few times - it’s much faster than the other pulses I pick up down there, sounds like it does at the doctor’s office. But the Doppler doesn’t register the heart rate, despite its audibility. I’m 15 wks 1 day. Anyone else have this happen early on with a sonoline b?