The HR reading looks fine until November 7th, but from Nov 8th I cannot get a read above 161 no matter how hard I train. I can't remember if I changed any important setting around those dates. I probably did since it is a new watch, but I don't think any setting is meant to introduce a cap to the HR reading.
These are all work outs that I pretty much maxed out. As you can see, the wrong reading also impacts Training Effect and everything else that depends on HR.