Now in friday facts I saw, that there were some changes made to items on belts and how they move to avoid "empty" places on the belts. Maybe there is a problem with this?
First the situation - I attached a screenshot.
As for my "factorio knowledge":
-The spot (red square) of the main belt is fed by the successing items on the same belt (1) as soon as items are removed further down the main belt (not on screenshot) by inserters.
-Belt lane No. 2 will never deplete, as long as there are oncoming items from the main belt (1).
-As soon as the spot (red square) is empty, the side belt (2) will feed the main belt and the grinder will start to work.
-As soon as there are new items from the main belt (1), the side-belt (2) will stop providing its items.
Now... I now saw my grinder on the left working, stopping, working, stopping, working, ... but neither the squared spot, nor the main belt (1) was empty. So there was no space to move the side belt's items, so the grinder could work. But well, the side belt (2) sometimes fills the spot with its items and the main belt's (1) items stop moving for a short time.
If I'm totally wrong here - forgive me - I'm no factorio nerd and just thought I "understood" the mechanics in this game.
EDITED:
I provided a video (attached file) of the behavior. I removed all inserters, so the situation is isolated and broke down to basics.
