You didn't check the busy condition as one of the conditions when setting up the forwarding path.
Apologies for my ignorance, but is this one of the indicators in System > Devices and Feature Codes > Phones > {extension} > Forwarding Paths > 1 ?
If so, it looks like all the flags relevant to Busy are set to Yes. The flags there all match the flags for the forwarding paths on an extension that is forwarding as we want it to.
Do you work for a VAR or are you the customer?
If you are the customer you may want to get training from your VAR and if you are the VAR you will want to get training from Mitel before they remove that as an option.
I'm a customer. The main tech with the VAR who serviced us left his company and went to another a few months ago. I've been trying to sell my boss on switching to his new company, but no luck so far. I've heard from a couple sources that the VAR is getting out of that particular business.
The boss has expressed interest in getting a new phone system sometime next year. But in the meantime, someone needs to know how to do a few things with the current system, and it's basically fallen on me. But I'm mostly starting from scratch.
I have been thinking about creating a Udemy course for the MiVO-250, but I don't know if it would be worth the time.
You have to do what's best for you, followed by what works best for the most people. But to the extent that my vote counts, I'd be for it.