Problems with flashcards

I currently have over 5,000 flashcards in the program. I always make my revisions through the queue, believing in the program’s algorithm. But today I was manually reviewing some materials and realized that there are cards that have never been reviewed in more than 1 year of using RemNote. The program never sent any cards for my review! I went to manually review these and there were the options to review in “24 hours”. How can I trust RemNote? The algorithm doesn’t actually send us all the cards!

My review process is making 250 cards in line every day! I’m using version 1.3.15.

Maybe you can find some answer in this thread.