The problem is you have more than 100 spawners and this happens.
You can set the first 99 to spawn as you are already then manually spawn items on the next 99 or whatever after like 1 second on a trigger i think that will fix it.
I tried it but it worked for the first 100 ones. The moment I tried to spawn next 100 using another button, the glitch was back. Thanks anyway for trying to help
It’s not a “Glitch/Bug” a server can have up to 100 dropped items, when a new item is dropped or spawned an old one has to de-spawn, thus making the item spawner think that the item was picked and to start the spawning of a new item (If Item Respawn is set to ON)