SpeechBackground does not work

Hi
I use Freepbx (Asterisk 18.20.2)
At the SpeechBackground stage, it throws an error "exited non-zero". The call ends, the sound is not played.
What could be the reason?

log
```
Goto (stt,s,1)
-- Executing [s@stt:1] Answer("PJSIP/1001-00000012", "") in new stack
-- Executing [s@stt:2] Wait("PJSIP/1001-00000012", "1") in new stack
-- Executing [s@stt:3] SpeechCreate("PJSIP/1001-00000012", "") in new stack
-- Executing [s@stt:4] SpeechBackground("PJSIP/1001-00000012", "custom/present_1") in new stack
== Spawn extension (stt, s, 4) exited non-zero on 'PJSIP/1001-00000012'
```

extension
```
[stt]
exten => s,1,Answer()
exten => s,n,Wait(1)
exten => s,n,SpeechCreate
exten => s,n,SpeechBackground(custom/present_1)
#exten => s,n,Verbose(0,Result as ${SPEECH_TEXT(0)})
exten => s,n,Hangup()
```

The sound is played quietly through the Playback.
Server Vosk is up and running through python in a dialplan.
Example
`exten => s,n,Set(RESULT=${SHELL(python3.6 /home/vosk-server/websocket/test_srt.py .....`