Hi,
A friend of ours can't join because they're not on the "whitelist" but we don't have any control over the whitelist. Her username is Merga and mine is PaperSailboat - I am the owner on the server. I expect that anyone I invite should be permanently allowed to use the server. If you do not wish for me to look for other services, I expect this to be remedied ASAP.
Thank you,
A concerned customer
As an owner go to Realms admin menu, under Players:
Name of invited players appears on the list.
Name is gray if they did not accept the invitation.
The name will be white if they accepted.
With other issues please contact Mojang Support