Dutch: Strengthen Skill omits some skills.
I have done the dutch tree up to "Formal, Present" and I am doing a lot of strengthening. But the skills "Possessives" and "Adjectives Basic" are decaying. I "never" (I can't remember the last time) get words out of these skills when doing general strengthening. If I go directly to those skills I can strengthen them fine, but I prefer a good mixture of questions with "Strengthen Skills".
Is this a Beta Problem or is this a system Problem with Duo? Can I do anything about it?