Family member doesn't receive any invitation after sending it

[bigjack48]

Hi, 

I got Spotify Family plan since more than a year, and it worked just fine since a couple of days ago when my girlfriend was suddenly without any family plan membership, she has now just a spotify free version on the phone.

I tried to send her another invitation, but she couldn't receive any message in the mailbox or in the app. 

I did it all on my profile page on the browser not in the app. The page told me that an invitation was sent. 

Are we doing something wrong? Why suddenly she is unable to use the family plan she used for more than a year?