It seems I am experiencing a bug when working in MSE for some weeks. When I edit my answers/questions for the second time, the online displayer does not work on any devices (i.e., I cannot see any preview of the changes before confirming the edit). I don't have this problem in meta or CV, or when I type my answer/questions for the first time in MSE.
How can this be fixed?
PS: I asked this question also in an SE chatroom on latex, and the members advised me to post it in the relevant local meta site.