New user does not show up in Assignee nor in Mention list

[Jorge Mendes Dias]

I'm running the free version of Jira. Yesterday I added 3 new users to my Jira. Just a reminder that the free version allows only team-managed projects, so keep that in mind.

1 of the 3 users can create tasks/stories/anything but does not show up in the Assignee field nor in the Mention (@) list in every issue but the ones this user creates.

So, if I create a issue I cannot assign the issue for him because he does not appear in the list even after i type his full username. Yet, he can create and assign a issue to himself. And if I navigate to the issue he created, I can tag him and assign him only inside this issue.

Things I've checked:

1. He appears as a user in board, list and basically every other menu (JF icon).
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2. He does not appear in the access menu.
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3. He does appear as a active member of the Jira product exactly like the others.
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4. His role and other settings are identical to the other two.

Things I've tried:

1. Deleted him and invited again. Didn't work.
2. Checked global permissions.
3. Checked other similar questions and none were related to this kind of problem or did not solve it.

I don't know what to do anymore and how can I solve this.

[Trudy Claspill]

Hello @Jorge Mendes Dias 

Welcome to the Atlassian community.

Just a reminder that the free version allows only team-managed projects, so keep that in mind.

That is not a true statement. The Free subscription of Jira allows both Company Managed and Team Managed projects.

Has your subscription always been only on the Free level? Have you ever changed it to a trial of Standard or Premium, or paid for it to be a Standard or Premium subscription?

What does the project say the over all Access setting is for the project; Open, Limited, or Private?

[Jorge Mendes Dias]

I've redacted the part about team-managed restriction. I was sure that was part of the free plan.

My subscription has always been free. Never changed to other plan.

When I create a project, the only option given by the system is Open.