Refine Edge Brush Tool failing

I have to commend Adobe for improvements on the Masking brushes over the past year, the brushe has worked excellently and accurately more than ever over the past decadse. However something recently has interupted the brushes behaviour. Thje edge selection is not clear and define and picking up clouds and other objects normally not selected. I have tried every combination of the view mode and reselected default settings and tried again however I cannot get the brush to perform with its usually good selection. 

Ken 

PS Beta, latest version 25.5.0

Macbook pro 16 M2