I hear the problem is lazysync, which makes sense. It never was written assuming cross-realm. I'm tempted to just disable lazysync when an instance is found to be cross-realm. Anyone figured out an easy way to defect this?
Latest alpha (1100) addresses an issue with data collection zone filters not working as intended for Onyxia's Lair. The problem there is that the surrounding non-instance subzone has the same zone name as the instance hence the standard zone change events not triggering. The fix may have other side effects that I cannot really forsee so I'm keeping this alpha until I got some solid testing on it! Feedback welcome.
["message"] = "Recount-1100\\Tracker.lua:1162: attempt to concatenate local 'element' (a nil value)\nRecount-1100\\Tracker.lua:333: in function <Interface\\AddOns\\Recount\\Tracker.lua:322>\nRecount-1100\\Tracker.lua:644: in function `?'\nCallbackHandler-1.0-5:147: in function <...onLoader\\CallbackHandler-1.0\\CallbackHandler-1.0.lua:147>\n<string>:\"safecall Dispatcher\":4: in function <[string \"safecall Dispatcher\"]:4>\n<in C code>: ?\n<string>:\"safecall Dispatcher\":13: in function `?'\nCallbackHandler-1.0-5:92: in function `Fire'\nAceEvent-3.0-3 (Ace3):120: in function <Interface\\AddOns\\Ace3\\AceEvent-3.0\\AceEvent-3.0.lua:119>\n\n ---",
["type"] = "error",
["session"] = 121,
["counter"] = 2,
}, -- 
Occurred at one of two times (yep, I forget which it was; might even have been both as it repeated): either a cross-realm random 5-man heroic dungeon (UK) or an own-realm 10-man OS raid that didn't last long.
I am aware that pets/guardians are currently bugged in cross-realm content. That is pets of players in other realms are not handled correctly. Unfortunately it's notoriously hard to debug, because I need to luck out on random groups that have pet classes (and EU realms just went down). This is a non-trivial fix, but I hope to get it done as soon as I can identify the root causes of the problem.
I just committed a version that passed my initial test. This should work for most cases but I am aware of pathological configurations where this can fail. I'll be working on a full solution, but this hopefully should work well for virtually everybody until then.
Completed debugging and reworking cross-realm pets. Should now work fully. Let me know if you see any weirdness. Correctly labeled pets now show as PetName <OwnerName> for same realm party members and PetName <OwnerName-OwnerRealm> for cross-realm pets.
Is there any chance to remove Mark of the Fallen Champion (Deathbringer Saurfang ability) from the effective healing? Some sort of filtering it or... whatever? 'cause it results in a really really weird healing meters, along with the Rune of Blood, and doesn't let effective tracking of the healing.
I'm trying very very hard to avoid adding encounter specific code to Recount.
I assume you are saying that the heal is attributed to the player who dies. But the detail breakdown should still clearly show which ability contributed what so people who want to understand what happened.
Now I could filter healing NPCs generically but I prefer not to do that because some encounters have that is a net positive.
This isn't the first encounter that causes players to heal an NPC. Illidan also did that. I think Recount's goal is to sensibly reflect what happens in the combat log, not to try to be the perfect representation for every single fight. Through the detail view also in the Illidan fight everybody could understand what happens, including what effect caused what heal.
I think it's best to keep that philosophy or else I'll be recoding Recount for a lot of boss encounters and turn the addon into a boss mod, which it is not.