Word counter astray

At lunch time I had 82,500 items learned. I learned another 15 in one Spanish course and now my word counter is 82,498. How come???

this is not the first time this is happening…

Could someone have deleted some words you have already learned from a course?

ahem, nope, that did not happen (it was my own course). I suspect has something to do with the high number of my items, and with the fact that - maybe???, i am telling myself - the “ignore” used here and there does not "always reflect itself immediately the items/word counter?