QB is flaking out. Giving link errors. Not sending invoices to valid emails. Is there a known system problem that has come up in the past few days?

Yes. We have an ongoing issue about this error, NeonLynn.

For now, the impacted region of this issue is for the United Kingdom. Since you're experiencing the same with the United States version, I'd recommend reaching out to our Phone Support team so we can report and investigate this one.

Also, if you want to take and process payments online, you can send an online invoice. I've added this reference as your guide: Take and process payments with QuickBooks Payments.

We appreciate your patience while we're working to resolve this matter the soonest. Keep safe!