Is this an avpd trait or something else?

focusing alot on people's facial expressions and not being able to process what they are saying?

Usually that gets thrown under the umbrella of autism.
Really, though, reading human facial expressions is a learned and developed social skill, and if you weren't a terribly social child, there is a high chance that you never honed this skill.

In many ways, this can benefit you. There are a lot of very good liars in this world, and reading their facial expressions is what they want you to do. Judging people by their body language and facial musculature is pretty superficial anyways. Pretend you're blind and simply listen to what they have to say without pushing in preconceived notions. The world would be a much better place if everyone did this.

Focusing on facial expressions is, but not being able to process what they're saying is not. And the reason you focus on facial expressions is to better understand whether they like you or not.

It's hard to say, it can be something different from person to person.

It might be an anxious trait. You might be trying to read the person instead of listening to what they are saying in an attempt to see if you can find out what they're thinking or planning to do. That is the main purpose of trying to read non-verbal language...that and trying to see if the person is lying.