Users cannot access to Confluence due to "XXX has reached its license limit" even though user count doesn't exceed the limit

Issue Summary

This is reproducible on Data Center: (no)

Steps to Reproduce

When a user who's been invited to the site tried to access Confluence , the error message below displayed and it was unreachable.

You don't have access to hnishida.atlassian.net
XXX.atlassian.netがライセンスの上限に達しているため、メールアドレスXXXにはアクセス権がありません。
(Your email address XXX doesn't have access because XXX.atlassian.net has reached its license limit.)

The number of guest accounts doesn't violate the rule below.

Expected Results

The user can access the Confluence page.

Actual Results

The user can not access the Confluence page.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available