so I have this basic flying machine I built using a youtube video… i've had this world since the beginning of this year and it was working fine but suddenly it stopped and I rebuilt it, but once I start it by placing a trapdoor on top of the nearest observer it goes like normal but doesn't bounce back on the other side. not sure if an update broke it or what I'm on 1.21.10 optifine. both sides the obsidian and observer with a repeater look exactly the same on both sides (2nd pic is other side).
by Comfortable_Bear_320