Known limitations

Things the plugin does not do, or does imperfectly, that are already understood. If you hit one of these there is no need to file an issue.

Bars and numbers

Other players' bars are percent-only. The game never sends another player's max HP, so there is nothing to turn their bar's ratio into a number with.
An NPC with no known max HP falls back to a percentage. The number comes from a bundled table of roughly 4,100 ids; anything missing from it shows a percentage instead. Missing NPCs are worth reporting.
ToA minions show a percentage in a team. Party-size scaling is documented for bosses only, so a minion's number would be a guess. Bosses keep their number.
Aggression is one answer per monster. A monster aggressive in one location and tolerant in another is marked the same way everywhere. The marking still clears when the game's tolerance timer expires.
The Ironman grey-out is inferred. It follows another player's hitsplats and the game's own no-loot message rather than the game's internal verdict, so it can lag a moment behind.

Bars bob during some attack animations. They anchor to the actor's model height, and some animations change it, so bar, name, icons, hitsplats and chat text move together for the duration. Affects you and other players.
Stacking only covers actors on literally the same tile. Bars on adjacent tiles can still overlap at low camera angles.
A bar jumps when its tile starts or stops being shared. That is stacking engaging or releasing.
A stack can sit as a slightly staggered column rather than a perfectly aligned one.
Stack limits drop an arbitrary actor. Which bars survive an NPC or player stack limit is not nearest-first or any other order you can rely on.

See Overhead replacement for why these exist.

The status-effect icon row can overlap overhead chat text when both are showing.
A hitsplat can change slot in the diamond. When an older splat expires the survivors are re-laid-out, where the game keeps each splat in its slot until it dies.
Only one set of overhead icons is drawn per tile. In a crowd, other players' prayer icons and skulls other than the tile owner's are not drawn. Your own always are.

See Shield and charge bars for how these work.

Doom's shield strength is derived from damage, because the game never transmits it. Anything that hides a hitsplat from the plugin leaves the number reading high until the next shield begins.
Shield and charge bars cover only the listed encounters. Any other boss with a shield or a wind-up draws a normal HP bar, and the game's own bar for that mechanic stays visible.