I have the Samsung Galaxy S4 and here is what I do to upload photos. See first image for choosing photos from your camera. Tap on and activate camera photos using the camera up icon. This will show Albums. Choose one and see next photo below for choosing images and uploading them to your My Cloud.
After choosing the photos you want to upload by using the check mark to select all or you can select individual images by taping on them, then tap on/activate the upload icon.