Not getting credits for skill strengthening
Twice yesterday and one out of two times today I completed skills strengthening but it didn't go through to the points credit page and therefore I lost them all.
Is this a known bug? I did email the help desk yesterday but expect they are very busy.
This is a known problem. Duolingo will "hang" after you answer your last question in a session and you don't get credit for having done the session. Some folks say that once they experience this problem they continue to experience it for all subsequent lessons until they restart their browser or maybe clear their history/cache.
That usually clears it up for me for quite a while. Like, several days or even weeks.
Frequently I'm too lazy to clear cache/history or restart my browser and I just do another lesson. Usually subsequent lessons don't hang for me (but like I said, some folks say once they get a hang, all the lessons hang until they clean things up).