Whenever the vanilla XP command is used to subtract experience orbs, the behavior they exhibit is unprecedented.

As a bit of background, my server uses command blocks to act as XP Shops for the players to buy items using their XP orbs. Originally, we were using the Essentials /exp command, but after discovering that the Essentials implementation had a game-breaking issue of its own (which will be filed separately), we began using /minecraft:xp instead.

One feature we have is an XP Bank which exchanges experience orbs for Bottles 'o' Enchanting, but we have found we cannot subtract experience orbs using the vanilla XP command. Whenever we try subtracting experience orbs using a command such as "/minecraft:xp -50 jflory7", this error is output: "Cannot subtract negative experience."

However, it IS possible to subtract levels (e.g. "/minecraft:xp -50L jflory7") which is what leads me to think this may be a bug.

Any additional information available on request.