Sorry to hear about this problem. I understand that you are wanting to be able to see the Activity tab on a Jira issue, but are unable to do for some users.
There is no setting for this feature to turn that on or off. So I'm not sure why you might be having this problem. It looks like you are the only user on the Cloud site we know about for your account (https://test***.atlassian.net). Which makes me wonder that perhaps if your team mates are having this problem it's on another site, or possible even a Jira Server/ Data Center site. Perhaps you have an account on another address somewhere else?
Could you let us know exactly which site you are visiting (or your team) when this problem happens? The full URL might be helpful as well so that we can better identify the platform and whether or not you are using the old issue view or the new one. I am afraid the screenshots provided just don't have sufficient information in them for me to understand if this is Cloud or server yet. If this is Jira Server, I would be interested to learn what version this is. If this is Jira Cloud, then I would want to know more about which Cloud site URL this is.
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