I have jot down few points to check why My Photo Stream is not working in your iOS Device & syncing Photos across iOS & OSX devices.
Solution & Few Check Points:
- You are sign in to iCloud using your preferred active Apple ID
- ‘My Photo Stream’ is checked & on your device under iOS Settings App under iCloud Photos related Section
- Your iOS Device has sufficient or more than 20% battery resource or at list connected to power adapter
- You are connected to high speed WiFi Network to enable iCloud to sync photos using My Photo Stream feature
- Camera App is not running in foreground or background
I hope this information helps,
Thanks & Regards
Mandar Apte