[Bug] Preonic startup sound broken after firmware update

After updating my fork of qmk_firmware after a long time and re-flashing, the startup sound of my preonic doesn't work anymore. Other sounds work.

Describe the Bug

I have set in rules.mk:

AUDIO_ENABLE = yes

and in config.h:

#ifdef AUDIO_ENABLE
    #define STARTUP_SONG SONG(PREONIC_SOUND)
    // #define STARTUP_SONG SONG(NO_SOUND)

    #define DEFAULT_LAYER_SONGS { SONG(QWERTY_SOUND), \
                                  SONG(COLEMAK_SOUND), \
                                  SONG(DVORAK_SOUND) \
                                }
#endif

In the past this was sufficient to get the startup sound when connecting the keyboard via USB. Now, I don't hear a sound. I can manually press the key for "AUD_ON" and get a audible feedback for that press, but startup sound is not enabled.

System Information

• Keyboard: Preonic
  • Revision (if applicable): rev3
• Operating system: Mac OS and Ubuntu
• AVR GCC version: 8.4.0

• ARM GCC version: 8.3.1

• QMK Firmware version: 0.14.3

• Any keyboard related software installed?
  • AutoHotKey
  • Karabiner
  • Other:

Additional Context

I did not update my firmware since about spring this year. I did not need AUDIO_ENABLE = yes in my rules.mk back then, startup sound worked out of the box.