Tactics Trainer bug

I recall this coming up in beta, not sure if it was ever fixed, but it's happening to me again: Sometimes I'll complete a problem, get it right, and get negative points to my rating.  This doesn't happen on the web site:

FWIW, here is the relevant Tactics Trainer history from the web site:

try getting a problem right on the website after a VERY long time - you will still get negative points.

How does the time and rating work?

The Chess.com Tactics Trainer uses the same Glicko rating style used in our Online Chess and Chess Mentor. Essentially you are playing a quick game against the problem! If you make all the correct moves you can achieve up to a full point for a win, and if you fail then you get a partial score based on how many correct moves you made. This "move score" is then adjusted based on how long you took to solve (or fail) the problem compared to the average solving time. Those scores are put into the Glick forumlas and then both your rating and the problem's rating are adjusted.

The chart below shows how your "move score" is adjusted based on your solving time.

so if your rating is high enough, it dont matter if you get it right. same thing with getting a few moves of a multi-move problem right, you only get partial credit.