Photoshop 20.0.3: Crop tool issues

1.- When I make click in the canvas with crop tool selected the "thinking" cursor appears for a second; next I'm able to use it... BUT...
2.- But sometimes suddenly the crop guides don't appear (as when we make command+H). That is to say: the "extras" are not shown. I have left PS, rebooted the Mac and everything remains the same. 

IT SEEMS that if I open another file, everything works fine again (I'm not sure yet if this would be a workaround). I would appreciate any idea.