@sofy As the other member mentioned, the issue is from Object cache pro. I cannot disable this plugin because it is good for speed. I asked cloudways (my host) to help me to exclude wpforo from object cache pro and they directed me to this page https://objectcache.pro/docs/ignoring-groups . Basically, since the plugin does not have an exclusion option, one has to configure the wpconfig by identifying the cache group that has to be excluded. However I am unable to locate wpforo's cache group to add in the wpconfig. Please check the link in this post.

@sofy Also yes my wpforo is updated. I checked on my staging website which is an exact copy of my live website (it also has object cache pro) and there is no issue on the staging site:

Look at the staging site's forum page: 

https://wordpress-601622-4412931.cloudwaysapps.com/community-forum/paradigm-shift-internships/

vs 

Live site: 

https://www.paradigmshift.com.pk/community-forum/paradigm-shift-internships/

I asked some other people to open the live website and they are saying the live link is working fine for them but not me. I am very confused.