Voicemails not saving

I have a client who claims to have left multiple voicemails over the last couple of weeks. I see the missed call in my log but no voicemail (not on the phone app, desktop app and I'm not getting an email).

This client has a tendency to ramble in messages and I'm wondering if she's hitting the time limit for messages and for some reason it's not saving? Is there any way to fix this?