I’ve been using Vlarya’s frequency list lessons and it had been going alright at first, but there is a problem with some of the verbs in testing and review. Though it has a prompt for one to select bubbles of full words. Among these bubbles are the correct imperfective and perfective infinitives, such as давать and дать when the prompt is translating “to give.”
The error I keep getting is that the program will only recognize the imperfective, but mark the perfective form as wrong, even when it is correct.
There seems to be a site-wide problem with the “bubbles” questions (which Memrise calls “Tapping tests”). I don’t know for sure, but I suspect what you’re seeing is just a manifestation of this same problem.
Actually, what I’m finding is that I can enter either the perfective or the imperfective by itself, but if I try to enter both (whether or not they’re separated with a slash) then it marks the answer wrong.
Personally I think the best solution for now is to just deactivate “Tapping tests” (go to Settings -> Learning).