I think this is a dragonborn bug :/

I found two bugs at the wiki page that I think may be the same as what you're getting. I'll paste them here:
Miraak won't be impaled by Hermaus Mora and gets stuck under the goo pile in the middle.
A possible solution is to use the moveto player console command to move Miraak back up to the arena. Then using SetStage DLC2MQ06 500 will end the quest and SetStage DLC2MQ06 580 will bring up the book to get back and get the cleared perk. Miraak's body cannot be looted, but the command openactorcontainer 1 will allow the PC to retrieve the items. There will be no animation or dialogue, but apart from that it proceeds as normal.
Or...
After Miraak absorbs the three dragons souls it is possible that he will not be killed by Hermaeus Mora. The Mora dialog in the center pool will occur, but he will never appear, making it impossible to finish the quest.
A solution is, in the console, to type in SetsStage DLC2MQ06 500 to finish the quest, then use SetsStage DLC2MQ06 580 to bring the book up to be able to pick a perk and get home. With this method, Miraak's body can not be looted for his items.

this never happend before, only after i got this mod after i took the mod off and reloded and fought him he died properly. also the glitch that happens is him not rising after he is beaten, or another is him not exiting ethereal form after consuming a dragon soul and being left unable to hurt him. a solution i heard about for the ethereal glitch is to use the resethealth console command after he consumes a dragon soul.

Yeah i've had this bug as well (Miraak gets impaled but he will just stay there forever, making it impossible to choose a perk/go back to solstheim). I deactivated the mod and everything worked just fine.

got same bug here :/

I don't know if this is only me but the courier never comes :/

@Ninoface He's busy taking over New Vegas.

He adresses this in the mod description. You need to deactiavte the mod, defeat Miraak, then reactivate the mod for this to work properly. The more 'ya know.

this bug appears when you use any mod that in any ways alters the dragonborn dlc...ik cuz i use miraak follower mod. its unavoidable unless you use console commands. i wish somone knew how to fix it though.

Guys read the Description oO... deactivate the mod kill him reactivate mod... its a known problem thts listet...

Miraak on tenticle: "I can see clearly now that im up way here!" - 4th era where dovahkiin broke him badly.

Probably Necroposting but bug is still occurring even with the mod disabled. This is the only mod I've ever used that has this bug reported with it