Blood oxygen on watch 4

[Juneyie]

Help.I have had my watch 4 for over a year and it's been great. Unfortunately it now won't do readings for the blood oxygen. It tells me to hold my watch nearer my heart or move watch further up my arm etc etc. Everytime I run this it always stops at 27/28%

Why is this happening

Please help.

[xMATHARUx]

Did you try a factory reset of the watch? If not, first back up your watch settings and then try it after