Actually, all apps on Play Store and App Store might develop some issues and can be caused by your phone or from the app developer.
How to Fix Snapchat Not Working on Mobile Data Android or iPhone?
1. Update Snapchat
This should be the very first thing you should do if the Snapchat app not working on mobile data. Updating the Snapchat app might fixed the error. App developers fixes their apps glitches whenever the released a new update, so updating the app could help.
2. Check if You Have a Data Balance.
This should be the first option to try when the Snapchat app not working, check if you have a data balance.
3. Restart Your Phone & Clear App Cache
Restart your phone and clear the app’s cache. This error might be a little one, so restarting your phone could fix it and also clear cache.
4. Reinstall Snapchat
Reinstall the Snapchat app, this might fixed the issue.