My Cloud Mirror can't be found on my laptop without any reason

I have a problem maybe some can help me with.
Out of the blue I can’t reach my WD Cloud Mirror via my Apple Macbook.
The drive is still listened as a available hard drive and I can access the first layer:
But if I want to actually open one of the files I get the message he can’t currently find the
»original file«.

About the same time this happened for the first time I have downloaded the My cloud app and got successfully access to my files via my iPhone.

So I thought maybe this was due the app and then erased the app again from my iPhone.
But that didn’t helped.

Any helpful ideas?