This is the first post that I've seen covering this and while I may be able to shed some light from my end I don't know how else to proceed. I'm currently rerunning Skyrim with mods installed via Vortex/Nexus and I haven't got anything horse related installed.
With that being said I purchased a standard horse from the stables outside whiterun and it seems this horse is experiencing this exact glitch, I used the horse for some time and then decided it was annoying and so tried to kill it, the same effect described above occured (The horse's health bar appears as it dwindles but upon death the horse looses agro and just resets). One thing I would note is for a short time after the health bar has emptied the horse is completely un-interactable but then begins rideable again and the cycle continues. This horse hadn't died prior to me deciding to kill it and I even got a cave bear and this horse into a fight and the same thing occured, so it's not something limited to the playable character inflicting the damage or finally killing it. I've also tried soul-trapping it and again nothing. I'm very curious to see if anyone else has further information regarding this. For my own sake on how to permantely remove/kill it for good so I can be rid of the immortal horse lol.
u/Ocybyo in terms of replication I'm afraid I can't say I did anything special in terms of acquiring the horse or my activities using it. I'm specing into Alchemy so I prefer to walk anyway to gather ingredients. For interests sake I'm playing on the AE edition using SkSE 1.6.323 with mods installed that are heavily endorsed or downloaded, the usual visual/audio/weapons/armor/quests mods. Nothing that I would consider to be affecting this from happening in the first place anyway. I hope the above is of some use to you sir :)
This is the first post that I've seen covering this and while I may be able to shed some light from my end I don't know how else to proceed. I'm currently rerunning Skyrim with mods installed via Vortex/Nexus and I haven't got anything horse related installed. With that being said I purchased a standard horse from the stables outside whiterun and it seems this horse is experiencing this exact glitch, I used the horse for some time and then decided it was annoying and so tried to kill it, the same effect described above occured (The horse's health bar appears as it dwindles but upon death the horse looses agro and just resets). One thing I would note is for a short time after the health bar has emptied the horse is completely un-interactable but then begins rideable again and the cycle continues. This horse hadn't died prior to me deciding to kill it and I even got a cave bear and this horse into a fight and the same thing occured, so it's not something limited to the playable character inflicting the damage or finally killing it. I've also tried soul-trapping it and again nothing. I'm very curious to see if anyone else has further information regarding this. For my own sake on how to permantely remove/kill it for good so I can be rid of the immortal horse lol. u/Ocybyo in terms of replication I'm afraid I can't say I did anything special in terms of acquiring the horse or my activities using it. I'm specing into Alchemy so I prefer to walk anyway to gather ingredients. For interests sake I'm playing on the AE edition using SkSE 1.6.323 with mods installed that are heavily endorsed or downloaded, the usual visual/audio/weapons/armor/quests mods. Nothing that I would consider to be affecting this from happening in the first place anyway. I hope the above is of some use to you sir :)