Coolant leak?

Definitely have a cooling system issue with it overheating. There are several reasons why your engine would overheat.

If there are no leaks when the cooling system is pressure tested but the coolant level is dropping the coolant has to be going somewhere whether internally or externally leaking.

There is a possibility the cylinder head gasket has failed causing combustion gases to be pushed into the cooling system which usually pushes coolant out of the reservoir. Did the dealership perform a block check to check for combustion gases in the cooling system?

There are other possibilities and what you have described to me narrows it down to the head gasket. If the cylinder head gasket has failed it will consume coolant and can push it out the coolant from system. So, I hope it's not that as it's a large repair but that would explain why there are no external visible leaks and for the low coolant level and overheating.

Let us know what the outcome is with your vehicle.

I don't know what the dealership did. They had it running for several hours with the radiator cap off trying to get the air pockets out and it was still burping when they stopped. I don't know if it's related, but the check engine light came on and the camshaft position sensor for bank A failed, I guess. I have a new one and will put it in this week. I have an extended warranty on the car, and it's been great so far. I think I will take it to a different repair shop and have them do a diagnostic.

Thanks for that.
I'm still leaning towards a cylinder head gasket failure. If they tried to burp out all the air from the cooling system but it never ended after hours of running still pointing towards a failed cylinder head gasket.
The cam position sensor shouldn't cause this overheat or loss of coolant concern. So, this would be unrelated.

Thank you for the reply and I would be curious to know what they find if you wouldn't mind letting us know what the outcome is.