Problem (Summary): In User's Activity, I am able to see my event but when I open it's details, the event parameters values are shown as (not set).
Journey so far: I posted a question: When exploring a user in GA4 User Explorer, how can I view the parameters passes through that event? and have since moved further, only in diagnosis, and not in solution. Thus, posting again with more data and full context in hope of getting a solution.
I am integrating GA4 on my website. The integration is through Google Tag Manager. I created an event Tag with event name page_view_manual (because the inbuilt page_view is also giving same issues, so just wanted to be sure). In this, I passed Event Parameters page_path & page_referrer, settings their respective values in Tag. I also added both page_path & page_referrer in custom definitions as Dimensions with Event Scope. 
I then checked in Tag Assistant that the tag is firing. I also checked in GA4 Debug View 
that the page_path & page_referrer values are being received by GA4 alongwith the event name page_view_manual.
Problem:
When I go to any particular User's Activity, it shows me a list of events for that user. I am able to see page_view_manual there. But when I open it's details, the event parameters values are shown as (not set).
Hoping that someone would have faced a similar problem and found out what the issue is. I already tried looking online but couldn't find much content around Event Parameter values in User Activity Tabs
