Stair count is low...

Just moved from a Fitbit Versa to the Vivoactive 3 and while there is lots to like, I can confirm the stair count is very low. I check the accuracy by climbing stairs at work and it is not counting them fully.  Should have been 4. Got 3. Went up a flight of stairs and got 0.

Morning walk normally 17, got 8 etc etc.

Any ideas? 

Running 6.90.