Rotary Encoder halts music with every turn

[SKHSKHilber]

I largely followed this https://splittscheid.de/selfmade-phoniebox/#5_3 and this http://www.gueffroy.info/index.php/phoniebox project.

In the latter one is creating a file mv ~/RPi-Jukebox-RFID/settings/gpio_settings.ini ~/RPi-Jukebox-RFID/settings/gpio_settings.ini.bak
nano ~/RPi-Jukebox-RFID/settings/gpio_settings.ini

[DEFAULT]
enabled: True

[VolumeControl]
enabled: True
Type: RotaryEncoder
PinUp: 12
PinDown: 23
pull_up: True
hold_time: 0.3
timeBase: 0.1
functionCallUp: functionCallVolU
functionCallDown: functionCallVolD

[PrevSong]
enabled: True
Type: Button
Pin: 13
pull_up: True
hold_time: 0.3
functionCall: functionCallPlayerPrev

[SeekBack]
enabled: True
Type: Button
Pin: 6
pull_up: True
hold_time: 0.3
functionCall: functionCallPlayerSeekBack

[PlayPause]
enabled: True
Type: Button
Pin: 5
pull_up: True
hold_time: 0.3
functionCall: functionCallPlayerPause

[SeekFwd]
enabled: True
Type: Button
Pin: 22
pull_up: True
hold_time: 0.3
functionCall: functionCallPlayerSeekFwd

[NextSong]
enabled: True
Type:  Button
Pin: 27
pull_up: True
hold_time: 0.3
functionCall: functionCallPlayerNext

Works all fine besides one issue: The Rotary Encoder halts the music every time it is turned to change the volume. Does someone have an idea what might cause this behaviour?