iCloud Photos no longer uploading
I've been using the new "iCloud Photos" to sync photos between my phone, iMac, and iPad. A few days ago, my photo stopped uploading photos. Under "Settings" > "iCloud" > "Photos", I see "19 Photos to Upload" and a progress bar that isn't updating. In Photos on my Mac, new new pictures are being added from my phone, but they continue to get added from my iPad.
I have already looked at this support page, but it doesn't seem to address my problem: Get help using My Photo Stream - Apple Support
I've tried turning "Upload to My Photo Stream" off and on. I haven't yet tried turning "iCloud Photo Library" off and on again, as it took my phone several days to sync initially.
iPhone 5s, iOS 8.3, null