Calling extension from the directory - no voicemail

I’m using the latest Disto FreePBX-3.211.63-9 and so far the set-up has been pretty straight forward. I have a small issue with the directory that’s accessed from an IVR. It works, but when the directory dials an extension, it rings the extension but never goes to voicemail if there is no answer. Voicemail works at any other time as normal, i.e. if the extension is dialed from the IVR, it rings then goes to voicemail as expected. Anyone have any clues why voicemail would fail when an extension is called from the directory? This seems quite odd to me.

So, it seems that FreePBX default behaviour is not to send calls to voicemail if there is no answer on internal to internal calls. External to internal calls work as expected and go to voicemail. The behaviour I’ve noticed is:
extension to extension = NO voicemail
directory to extension = NO voicemail
IVR to dialed extension = voicemail
IVR to Queue to extension = voicemail

Can anyone tell me how to change that behaviour so all calls to extensions go to voicemail if there is no answer?

BTW, if the destination extension is in use for internal to internal calls, it does go straight to voicemail, so that’s good, however if there’s no one there to answer the call, it just rings.