Hi emsilver,
Thanks for using Apple Support Communities. We understand you're seeing Ask To Buy requests going to one device and not the other. We're happy to look into this with you.
To start, make sure you're not missing those requests. Prior to them being approved, check if you're able to see them:
If you miss an Ask to Buy notification, you can find the request in Notification Center on your iPhone, iPad, iPod touch, or Mac. If you still don't see your Ask to Buy requests, check which Apple ID you're signed in with, check your Family Sharing settings, and make sure that you're on a supported device.
See more about that here: If Ask to Buy isn't working - Apple Support
Some other steps to resolve Ask to Buy not working as working as expected would be:
- Restart all devices: Restart your iPhone - Apple Support
- Ensure devices are fully updated: Update your iPhone, iPad, or iPod touch - Apple Support
- Make sure all devices are connected to reliable wi-fi / cellular data when request is sent
Thanks.