Not possible to @ mention users in Confluence Cloud

Issue Summary

Not possible to @ mention users in Confluence Cloud

Steps to Reproduce

1. Create a new page
2. Enter @ and start to type an user name

Expected Results

You should get a list of users who match the string you've just entered

Actual Results

No results are displayed.
Instead, an error message saying "Something went wrong. Try again in a few seconds." is displayed.

Workaround

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