TransferComponent in VAD does not play onhold.mp3

[len@Arena]

I have a flow which transfers a call using the VAD transfer component. The transfer works however whilst the transfer is occurring the client does not hear anything with the result that a lot of people simply hang up thinking that nothing is happening. Digging in the server activity log I found the following entry:
Cannot open stream source 'c:\programdata\3cx\data\ivr\prompts\onhold.mp3'
I browsed to the location from windows explorer and assigned the group everyone read rights to the file assuming it was a windows rights issue but the situation did not improve.

Any ideas? Same script worked fine under version 8, I am now running this script on a version 11 3cx.

 

[VAD_Support]

Is the audio file played if you make a regular transfer (not from the VAD)?

The VAD doesn't make anything special to transfer the call. It's just like any other extension transfering a call...