First, we'd recommend following the steps to invite your family members here in an incognito or private window in your browser. Alternatively, you can try in a different device.
Keep in mind that each of your family members will need to have their own personal Spotify account first. If they do, we'd also suggest asking them to double-check the email address registered on their Spotify accounts to make sure your invites are sent to the correct addresses.
If they're still having troubles seeing an invite to join your plan, we'd recommend giving it a try reinviting them to your plan:
Go to youraccount page and clickPremium for Familyin the menu on the left. Then, select the member you want to re-invite.
If that doesn’t work, clickCANCEL INVITEand re-invite the member by clickingSEND INVITE, and re-entering their details.
If that doesn't do the trick, make sure they check the following:
If they're accepting the invite on the same device it was sent from, make sure the owner who sent the invite has logged out of their account page first.
If a family member didn’t receive an email with the link, be sure to check the junk/spam folders in their inbox.