Photos are cropped after being shared from Photos App

So, I wanted to share Photos from my Photos App using iCloud shared albums. I have iCloud Photo Library enabled.

All the photos I want to share are perfectly uploaded to iCloud, as I checked them on my iPhone.

But when I created the shared album, some of the photos are cropped! The lower part is just plain white.

Some of them are missing 30%, others are missing 90%. Some are even all white. This is the case for every device I access the shared album from.

But the originals are still complete and not cropped (When I access them via "Moments" for example). That is on every device!

No matter where I access

I noticed, that when I shared the photos, the Hard drive of my iMac began to show heavy activity.

I imagine there should be no HD activity, since all my photos are in the cloud already. So when I want to share photos from my iCloud photo library, all the Photos App has to do is send the list of those photos I want to share to the iCloud servers. Not the entire (or corpped) photo.

Anyone else experiencing this?