USB-C to 3.5mm Headphone adapter does not work with iPhone 15 Pro Max - Solved

I wanted to listen to music or a metronome click track app via wired headphones with my iPhone 15 Pro Max.

I purchased the Apple "USB-C to Headphone Jack" Model A2049 MW2Q3AM/A from Best Buy.

To my chagrin, when I plugged in headphones using this adapter, it did not work! Sound continued to come from iPhone speakers & not the headphones. I was using cheap KOSS headphones (for the click track) so I switched to much better Sony headphones & same result. I plugged/unplugged several timers & no help.

I searched & found this closed Apple forum discussion:

iPhone 15 doesn't recognize USB-C a 3.5MM… - Apple Community

“If you go to control center ( pull the right corner) and tap the player, then tap the airplay icon ( up arrow with waves), can you choose the speaker/headphone?”

I tried that (IDK if I tapped the airplay portion) & in the upper right I had a rectangle "Player" but tapping it did nothing.

I then started the music & plugged in the adapter with headphones. (I don't recall the order of play & plugging in ) I than got a pop up asking if I'm using headphones & I tapped "YES"

It immediately worked & music or click track coming just via headphones & not speakers (Sony or KOSS)

So apparently starting music or metronome via the app will not be sufficient for iPhone to recognize headphones. You apparently must use the pull down menu & select player in order to get the pop up so you can select yes/headphones.

Strange.

HTH