Problem with tactics trainer

I am using google chrome browser , I solve a lot of tactics each day in chrome incognito mode recently i have been facing a new problem where after displaying problem solved or correct move it just simply stops instead of displaying the rating change or next move puzzle this happens many times , due to this problem i m not able to improve my rating as after reloading the page a new tactic appears and the same problem repeats

I put in a ticket to support and performed the traditional steps to clear temp and history. Clear about 4 weeks of history or (earliest time you noticed freeze) and then close the browser and start browser again. I have not had the "freeze in TT" since doing those few steps above.