How do I fix NPCs not showing a cast bar for some custom spells? - azerothcore

Question

I am currently creating a module that creates custom boss fights in vanilla dungeons. To accomplish this without having to make edits to existing spells used by other creatures, I've been using Stoneharry Spell Editor to create custom spells that the bosses use.
The spells that I created are doing exactly what I want them to do but the majority of the spells that aren't instant cast will not have a cast timer shown while the boss is casting the spell.
Some of these spells haven't been edited aside from the damage. Just a straight up copy of a basic spell like Lightning Bolt. I searched through all of the attributes and there was no difference between spells that would show the cast timer and those that wouldn't.
What determines whether or not a spell with have a visible cast bar and how do I fix the spells that don't?
I have gone through the process of creating a custom MPQ file to patch my client in addition to the server side DBC file.

Answer 1

I was unable to find the cause of why some of these spells were not showing a cast bar but I did find a flag that can be set to force the display of the cast bar as a fix to the issue.
Setting AttributeEx4 with the value 268435456 (hex value 0x10000000) will force it to display. I confirmed this flag worked with all of the spells that were previously not showing a cast bar.

Answer 2

Might be related, might be unrelated, but from what I understand the 3.3.5 client and blizz's own UI uses events in the combat log to show stuff like cast bars in the UI frame. And because 3.3.5 client famously has bugs that the combat log gets frozen and stuck, sometimes these things disappear. People also call this famous bug other names like the "recount bug", since it leads to addons like Recount showing the wrong values for damage and such, because they stop receiving the correct events from the combat log. Notable thing is though the bug is very strange, it does not always completely freeze everything but rather still let some of the events through, leading the numbers in damage meter addons to change but be completely wrong.
I have stumbled to the same problem with regular mobs and bosses, noticed that some of them suddenly stop showing things like cast bars and buffs/debuffs after the combat log bug happens. The bosses still make their animations for casting and stuff properly, but they don't show in the UI. That's what lead me to think that the stuff happening in the "world" are handled by server sending opcodes but the stuff that is shown in your UI frame are from the combat log.
So first make sure you're using a combat log clearing addon or a macro, like this one:
https://github.com/anzz1/CLFix
Yes, I know that code runs the CombatLogClearEntires() every single frame, but from what I have tested I simply found every other addon that clears the log more infrequently to the combat log bug sometimes happening. Only running it every frame has spared me from any more combat log bugs. See, the thing about that bug is that you have to clear the log before it happens, clearing it afterwards won't usually help and you need to reload the whole UI.
Secondly, what you could do is check what your client sees happening in the combat log by printing the combat log events and comparing the different spell events that way. This can be achieved easily by making a frame, registering the COMBAT_LOG_EVENT_UNFILTERED event and printing the results.
Like this, just wrap that code into a .lua addon to see what's what:
local f = CreateFrame("Frame", nil, UIParent)
f:SetScript("OnEvent", function(self, event, ...)
-- timestamp, eventType, srcGUID, sourceName, srcFlags, destGUID, destName, destFlags, spellID, spellName, arg1, arg2, arg3, ...
print(...)
end)
f:RegisterEvent("COMBAT_LOG_EVENT_UNFILTERED")