How can I restore global permissions for app users in Confluence Cloud?

[SaSa]

I am new to Confluence Cloud and I have installed an app.
On the View Global Permissions screen the app user was added as an individual user with the Create Space global permission.
I have revoked this permission - just wanted to try it out (on Confluence Server with which I work so far you can restore permissions).
But now a macro of the installed app no longer works for users who have only the space permission to read.
So I want to restore the global permission for the app user in Confluence Cloud.
But on the Global Permission screen stands:
"No data available - There are no apps installed on your site that use global permissions"
When I enter the name of the app user in the search box, it is not found ("No user group matches your search criteria. If you can't find an app, it may not have been added to the site yet"). But if I look to the installed Add-Ons the app is still there.
In the Atlassian documentation I cannot find any help, only about the normal user groups.
Does anyone have advice for me?

[Nic Brough -Adaptavist-]

Confluence does not appear to be serving anything up.

What does the server application log say?  <conflluence home>/log