The odd thing is that the issue is specific only to a sub-folder within Drive. If he tries to upload to the main Drive directory, the upload happens instantly.
FolderSync works only if I manually sync it. Auto-sync whether instantaneous or every 15 minutes does not work.
I’ve done the following things to try to repair this issue:
Force stopped the app and restarted my phone. (many times)
Disabled uploading only while on Wi-Fi.
Logged in and out of the app.
Cleared app cache and data.
Disabled (can’t uninstall the app) and enabled the app.
Cleared my mobile cache in OnePlus.
Disable power-saving and data-optimization for the app.
Granted all permissions to the app.
None of these things have worked or made the situation any better. I contacted Google Drive support and they said that if you can upload files without any issues then the problem is with the phone.
I contact OnePlus and the phone cache reset is what they advised. It didn’t work and now they’ve asked me to go to a service centre which I don’t want to because it is far away from my house.