When you give yourself a repeating command block it does not run.
Or.. just sometimes.
The Command Block is glitched and MiddleMouseClicking it does not work.
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Not sure actually. It's like a glitch that occurs when i enter a command and then the command doesn't get run.
I wanted this command: /execute as @a if score @s Y matches ..2 run say test
It did not say "test". then i copied it and ran it myself and it worked. Then i swapped the Command with a normal "say a" always active- repeating and it did not work.
I think i found out what is wrong. When I give me that command block, then change it to chained always active, and THEN swap it back to repeated it will not work
Ah, sounds like MC-86846

But it isn't fixed.
Hm, it is for me in 1.16. I'm curious, are you in 1.16 as well? The environment says 1.8, but repeating command blocks weren't even in that version.

I am in Minecraft 1.16. I am using Java 8. That's what i ment
Needs more information. What doesn't work? How is it glitched? They work fine for me.