Friend having issues with being invited to Playtest.

[Dinotacotherapy]

So. me and my friends have one friend that we have invited to the deadlock playtest numerous times. https://steamcommunity.com/id/MoxIsGlimmering/
And its hard to know why, even though Mox gets other playtest invites.
Screenshots are mox's. Mox is on the Discord, and has messaged Yoshi and another person. no responses yet.