WowAce

I don't think the values here are accurate.  I'm compared them to Hard Yards (https://wow.curseforge.com/projects/hard-yards?gameCategorySlug=addons&projectID=60094) and to my own spells and abilities in game.

For example: Melee range is 5 yards or closer.  I got close enough to a Dummy so that your addon displayed 0-4,  Hard Yards displayed 5.1-6, and I could not melee attack the Dummy.  Moving in slightly, Hard Yards changed to Melee, RangeDisplay stayed at 0-4, and I was able to melee attack the Dummy.

Hello,

  I've added some new items for range checking recently.  It is possible that some of them don't work correctly (or at least don't work correctly on all type of targets, like target-dummies).  I'll take a look at it.  (In this particular case the item that may be bugged is "Shoe Shine Kit")

Can you check the same issue with a player (in a duel, for example)?

I checked out the code and it seems impossible to get a "0 - 4" display from RangeDisplay in its current state.  Are you sure you're testing the latest release? (and are you testing RangeDisplay and not some other addon? :)

Will test in-game later though...

I double checked and its absolutely the RangeDisplay addon.  I also checked the value displayed on a Training Dummy and got "0 - 4" while in Melee.  I then dueled another character and now its suddenly giving ranges of "0 - 2" at Melee, that behavior is very odd. 

I tested these values after dueling and they seem to be accurate at long range.  Compared to Hard Yards, it looks like you two just have some different ranges.

However, it gets inaccurate under 7 yards.  I noticed that in LibRangeCheck2.0 you have the Worgsaw as a 5 yard check, while other sources have it listed at 6 yards.  Perhaps this is where it is breaking down?

There are two types of ranges, "distance from hitbox" and "distance from center". Many people do not know this which leads to confusion. For the purposes of all items, spells, and melee hits, only the "distance from hitbox" matters. Furthermore, melee range is defined as "0-2 yards from hitbox". In particular, melee range is not defined as 5 yards. In the case of the default hitbox size of 3 yards, melee range will be 5 yards from center; but hitbox sizes tend to vary wildly.

A range of "0-4" means that the addon is unable to distinguish the 0-2 and 2-4 range and thus cannot detect whether it's in melee. This is consistent with your results. BTW, the Worgsaw is in fact 5 yards, if you mouse over the Wowhead tooltip. Note that this means "5 yards from hitbox" and is thus not directly relevant to melee range.

But there actually is an underlying issue to why the range is showing "0-4". I've experienced this before and in fact the IsItemInRange() check for the intermediate-range item still works. It's due to the fact that on initialization, the item will not be added to the checkers list if GetItemInfo() returns nil. But due to items not being in cache / having to be pulled from the server, stuff that fails GetItemInfo() on initialization may be populated later. Possible solution would be to periodically query GetItemInfo() for populating the checkers list with exponential backoff.

After doing alot more testing, especially on large hitbox targets things feel alot better.  Especially now that I'm not constantly getting a "0 - 4" output.

Apparently the Worgsaw used to be 6 yards at some point in the past, which is why it shows up in so many range check lists as 6.  Also, I was going by the WowPedia definition of melee range that included the common hitbox size.  There is so much misinformation on this.

Thanks for explaining.

As for the "0-4" range issue, it definitely seems like a Caching issue.  As soon as I dueled someone, it worked fine.  I never duel, so it looks like it cached something.

I got the "0-4" range issue to come back when zoning into an instance, but it was fixed upon a reloadui.

probably fixed by now