Phone plays audio through speakers even when headphones are plugged in

I have a version 5.1.1 phone that I use for music and audio books. Since yesterday the phone will no longer send audio to headphones, but plays it through the speaker instead. The phone recognizes that there are headphones, as it shows the “Headset is plugged in” notification when it’s in. When I remove the headphones the phone recognizes that they have been removed as the phone pauses the audio.

I’ve plugged the phone into a speaker using the headphone jack and everything work correctly. I can then plug the headphones into the speaker and everything works. I found some old headphones that don’t have a microphone or the click to pause button on them and the phone plays into those headphones.

I have made no changes that I know of over the last few days. No new apps or anything. Any ideas how I can get the phone to play audio through the headphones even if the headphones have a mic on them?

Model number: A622GL

What I’ve tried:
Multiple headphones.
Restarting the phone.
Cleaned out the headphone port.
Tried multiple apps, all acted the same.
Tried the headphone with something besides the phone. They were fine.