Users still prompted to request access to report, even when Public

We have a Looker Studio report that is shared as Restricted with certain users, but the users in one domain are not able to access it. They receive the "Your current account can't access this report, or the report doesn't exist." message, with a button to request sharing. If they request access, the message we receive our end comes from the account that already has access! (So it's not aliases or something like that.)

We tested things out by sharing a Public report with these users, and the same issue happens...they see the message to request access.

This is a different situation/message than the users not having access to Looker Studio. (That message would say "We are sorry, but you do not have access to this service." or something like that.) Their Google Admin says that Looker Studio is enabled for all users and that the issue is on our end.

Does anyone have any ideas? We have lots of users in different domains but have never encountered this situation.

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