Apple Watch os2 update, now heart rate not working.

Today I updated my Apple Watch Sport to os2. Since the update the heart rate function is not working. Fitness tracking is turned on on my iPhone. It is in glances and does not measure a heart rate, I get an error saying try again. The watch is tightly on my arm as normal. No fitness activity has been recorded today despite me going on a 45 min walk.

I have no tattoos and no issues with my skin. The watch is clean and dry. Any suggestions? It worked fine before the update.