Problems with shared photo streams on MacBook

A shared photostream I created suddently "disappeared" from Iphoto. But I can still see it on my AppleTV. Any specific reason how this could have happened?

I changed my appleID on my Mac in the mean time.

Also, I created a shared photostream and added 3 pictures to it. For no specific reasons, the photos disappeared but the photostream remained on my Mac. Also, the pictures can still be seen on my Iphone. Any reason for that??? The photostream wasn't shared with anybody.