Is there a bug with half-life (non) progression?

I have been using LR to learn German daily for about a month now. After 4,171 repetitions for 68 “Learning now” words, the highest half-life achieved is only 0.79.

0.79?? Not even a day??

Is this normal or a bug?

I have used spaced repetition systems for 20 years and it looks crazy low to me after so many repetitions.

A year later, I have a similar problem. I have been practising some words for about 4 words and every time, their half-life only increased by about 0.1 every day. What is the interval ? It seems like it’s random. Normally, learning should be more spaced (and set) in terms of repetitions.

Can someone explain how the algorithm works, please ? It makes no sense to me. Thank you.