WD Elements

Hello, I have two WD Elements (2TB) with my backups done from a year, and they do not work in Mac anymore, only in PC.
When I connect them they are active (you hear them running) but you cannot locate as before, and when you manage, you cannot select it, it is in grey. I tried in other usb from the computer and it doesn’t work, but when I use another USB from other brand it does work.
Could you please, help me? Thanks