Steps to reproduce

1. Wait for some skeletons to spawn.
2. Walk up to the skeletons.
3. input the following command in the chat window

/effect give @e[distance=30,type=minecraft:skeleton] minecraft:instant_health 50

Expected Result:

The skeletons should have taken damage for a second or two, then died.

Actual Result:

"No entity was found" is displayed in red.

Note:

1. Omitting distance functions as expected.

2. My initial list of mob types was much longer, and all negations, but I pared it down and changed it to just skeletons determine which was at fault (distance or the mob list)

3. I want to create "spells" with limited reach. One set will harm undead. (Directly, setting them on fire, exploding them... you know, the fun stuff.) Without the ability to limit this command's reach, an entire subset of spells (direct damage) can't be crafted at this time.