Thank you Shin and Ann K Frailey for this suggestion.

With regard to claps, I think the problem is related to Medium backend systems.

Today, until 8 PM, my time, I tried several ways from my laptop such as refreshing screens, changing browsers, even using a different laptop. None of the claps happened all day. However, after 8 PM, claps started working.

It is hard to diagnose when there is no feedback from the server end.

Hope Medium support sees this post so that they can shed lights on this issue.