Can’t send emails with this app on an iPhone 6s

This app works great for receiving emails, but for the past month+, I have not been able to send emails or put on attachments, which makes the app pretty useless. I have tried uninstalling but that doesn’t resolve the issue. Is anyone else experiencing this issue? Is there a patch for this that somehow my phone has missed?

Sunny and cold? about Gmail - Email by Google, v5.0.171217