Hi there! I understand that the Canon PRINT app used to work fine but now it gets stuck on "processing" and doesn't move forward. Let's work together to get this fixed.

First, to get a clearer picture:
- Are you trying to print from a Windows 10 PC using the Canon PRINT app?
- Is your printer connected via Wi-Fi or USB?
- Has anything in your setup changed recently, like a new router, software update, or printer move?

While you check on that, here are some initial steps that usually help with this "processing" stall:

1. Restart your devices:
- Turn off your printer and unplug it from power for about 1 minute.
- Restart your Windows PC as well.
- Then, power the printer back on and open the Canon PRINT app again.

2. Check for app updates:
- Go to the Microsoft Store or Canon's site and ensure the Canon PRINT app is up to date.

3. Clear the app cache or data:
- Windows apps sometimes store cached data causing issues. Try clearing cache via Windows settings or uninstall and reinstall the app.

4. Verify printer connection:
- If via Wi-Fi, make sure your printer is on the same network as your PC.
- You can try reconnecting your printer to the network or connecting via USB to see if that helps.

5. Cancel any stuck print jobs:
- Go to 'Printers & Scanners' in Windows settings, select your printer, and open the queue. Cancel any pending jobs that might be stuck.

6. Check firewall and antivirus settings:
- Sometimes security software blocks the app communication with the printer. Temporarily disable them to test.

If you've tried these or they don't resolve it, a more targeted reset might help:

- Unplug the USB cable (or disconnect Wi-Fi on printer).
- Press the printer's power button multiple times (like 10 times) to clear any internal states.
- Power cycle and reconnect the printer.

If the issue persists, let me know any error messages or behaviors your printer shows (e.g., blinking lights, anything on printer display). That way, I can guide you further or suggest next steps based on your printer model.

Are you able to try these steps and tell me how it goes?