Simple - Either limit of entities (aka Beer / Food / Fruits) has been cut off, thus you cannot achieve +20k points/+50 combo, or…
They spawn inside Minigame PAD?! I’ve marked them on screenshot which you can recognize them by glowing effect.
P.S. This is really happened 1 hour ago in Food Frenzy, where almost no food left, thus i cannot keep my combo and it is genuinely angering me.