Since updating to lastest Lightroom Classic my masks wont select properly.

Hi, since updating last night my Lightroom Classic, (14.5.1) my masks wont select properly. If I do subject select it basically selects half a subject and the background, if I select background, it masks everything!   Almost like one big mask across the image, rather than how it was pretty perfectly selecting people.  Any idea's anyone please?

Deb