We apologize for the inconvenience.
Open your device's "Settings" app → "Apps" → "Smart Planner" → "Permissions" → "Photos and videos", make sure the app is allowed to access your photos, and try again (on Android 14 and later, if only some photos are allowed, please also see "I can only select some of my photos").
If you still can't attach photos, restart your device and check on Google Play that Smart Planner is updated to the latest version. If the problem persists, please contact us using the "Contact Us" button on the help screen and tell us your device model and Android version.