Hi, I have the same problem (achievements are not popped up) using learnDash as well. I bought all the addons and then realised that the auto message is very restricted to numbers and is not poping-up.
My website is still under construction and I would consider the use of BadgeOS only if a poping up feature provided (I prefer to use another limited achievement plugin with pop-ups if not)
So, can you promise that you will provide this feature (if you are working on) soon? and when expected?