Photoshop 21.1.0 Problem with Refine Edge

Since upgrading to this latest version I have found that using the Refine Edge Brush when doing Select and Mask doesn't work properly. Either nothing happens or the mask edge gets corrupted and "messy". This is happening on both a well spec'd iMac and also on a latest fully loaded iteration of the Mac Mini. Both are running Mac OS 10.14.6 (Mojave). Even calling up the old Select Mask via the Alt Key and then choosing Select and Mask doesn't fully resolve the situation. This problem is in addition to the problem with Shadows and Highlights Adjustment freezing Photoshop which I have reported elsewhere as have others and for which Adobe found a partial work-round which works sometimes but in doing so may possibly have caused this Refine Edge problem although I have no proof of this.

 Is anyone else experiencing similar and if so have you found a workround?

Adobe please deal with these problems with 21.1.0 as soon as possible.