Same here. Each day it serves the 50 new words before I've even gotten to my 100 cards for the day. It gives me the "pay us" interrupter message and the "practiced all words" message with, allegedly, the option to "Come back later when Lingvist's algorithm has got some repeat words that will need refreshing in your memory — or if you can't wait, hit the button below to practice a random set." but even though I have hundreds of words listed to practice pressing the button does nothing.
With this it actually feels like the site hampers learning, because it actively blocks me from the repetition that would help reinforce and learn the word. I don't know how this is supposed to get anyone to pay for the upgraded version if it can't even manage the most stripped down version of its basic introductory features?