Apple Music’s automatic sample rate matching/switching stops working on iOS when the display is off. Is there something I'm doing wrong?

Hi,

When the screen is off, the iPhone fails to automatically switch/match the output sample rate after a certain period of time, approx. 3 songs.

What is worse is that it fails to output any sound at all when the screen is off and when the sample rate that it stopped switching at, is too far from the current song's sample rate, for example: iPhone has stopped switching/matching sample rate at 44.1khz and the current song is 176khz, you won't hear anything when the 176khz song plays.

Here's how I tested this a few times and every time ended up with the same results.

1) I set audio quality for all options to Hi-Res in Apple Music (iOS)

2) I used a playlist where the first 3 songs are 24/44.1khz and the forth song is 24/176khz

3) I used another playlist where the first 3 songs are 24/44.1khz and the forth song is 24/48khz

4) I used my ifi xDSD Gryphon DAC connected to my iPhone 13 Pro Max with both 1) the official Apple CCK USB cable/adaptor, to test first and then 2) the lightning cable included with the DAC to test again.

5) I used my Sony WM1Z as a DAC connected to my iPhone 13 Pro Max via the official Apple CCK USB cable/adaptor

The displays on my ifi xDSD Gryphon DAC and my Sony WM1Z, both show the exact sample rate being output from my iPhone 13 Pro Max (iOS 15.2). Here's what happened:

While screen was off, the first 3 songs played at 44.1khz, the forth song was supposed to be 176khz but there was no sound output, tapping the screen to turn on the display brought back the sound but only at 44.1khz. Turning off the display stopped the sound output immediately.

Manually skipping back to previous song and then again skipping forward to the 176khz song, fixes this temporally, and the song starts playing at 176khz (I believe this is because screen is on), until it stops switching again.

The only way I've found to work around this situation is to turn off auto lock feature for the display on iPhone settings, and leave the display turned on the entire time during playback.

I also tested this (while screen was off) with 44.1khz with 48khz and encountered the same situation approximately after 3 songs, except this time, the sound output did not stop, it played but at 44.1khz and not 48khz. I think the sound output did not stop because 44.1khz and 48khz are very similar?

Using the same method that I used with the 176khz song, skipping back and forward, fixed it temporarily, because the screen is on.

Leaving the display on the entire time during playback and unlocked as a work around this is obviously not a good solution. Is there any other way to fix this?

Thanks.