I can receive but not send any iOS Invitation (Shared Albums / Reminders / Calendar events etc) I have tried everything I have found online and all the settings are in place. My wife can invite me to calendar events, reminders, shared albums etc. I, however, with the same settings I can not do it from any of my two iPhones or my Macbook.
I would guess it is a problem with my iOS account itself, but I do not know where the problem is.
Could it be it that I do not have an @iCloud account? My Apple ID is my gmail account.
Best regards
You need at least one account added on your device to be able to invite. You can add it on Settings &gt; Accounts &gt; Add Account.
If you have a provider specific app you may be able to use it to invite other users to calendar events without the previous step.
Shared albums should not need an account though, just the email or phone address associated to the Apple ID of your invitee, depending on the way you chose to send the invitation.