For some reason, /execute on origin doesn't work on Area Effect Clouds when the player has logged out, then logged back in again.

To replicate:

• You must be in a server or a LAN hosted world, but not as the world's host,
  and the area you're doing this in must be loaded.

• Toss a Lingering Splash Potion of any kind.

• Run: /execute as @e[type=minecraft:area_effect_cloud,sort=nearest,limit=1] on origin run say bug

• This should work as you'd expected it to.

• Now, log out and log back in before the Lingering Potion's cloud disappears

• Run the command in step 3 again

• It doesn't work anymore, but it should, as it's the exact same command, the exact same entity, on the exact same owner.

Note: This bug behaviour wears off only when the server restarts itself.