This is a patch for SmartBlueCat's amazing Inigo (for SE/AE), to prevent the Inigo-not-riding bug that can be triggered by taking any of his starting items from him when the user has both SKSE64 and RaceMenu installed.

This is still being tested, so keep that in mind, though it appears to work so far.

This does not solve the problem on a save once it has been triggered or once you have given Inigo a horse, and should be installed at the start of a playthrough, or as soon as possible.  So install it before taking any of Inigo's starting items from him AND before giving him a horse.  If you have already triggered the riding bug (by taking his things), here is a detailed guide on how to fix that issue, thanks to users Thallanar1170 and Congoryan, which involves using Fallrim Tools ReSaver (link to original post).

If you have already given him a horse, but have NOT taken any of his items from him, you can install the patch, but it may not prevent the bug from triggering.  If he has been riding for a while, but you have not taken any of his starting items, you can prevent the bug from triggering by using the console to make him drop all of his starting items.  Then you can pick them up and hand them back to him.  It should be safe to trade freely with him after that without triggering the bug (though the bug will remain in the pre-trigger state, it shouldn't affect his riding).  

If enough people try this, and report that it works with no unexpected effects, it will eventually be integrated into the Inigo main file.  As far as we can tell, this fix should not have any undesired effects on anyone's game, whether you use SKSE64 and RaceMenu, or not.  But then, the original problem was entirely unexpected, made no sense, and was out of left field on a mod version that had been stable and in use for years, so we need further testing to confirm that it does only what we hope.

This would be used instead of forcing Inigo to drop his things with the console, then giving them back to him (unless you have already given him a horse), and should entirely prevent the problem from the start, if installed soon enough.

It is very tiny, and only makes one small alteration to the faction setting on some starting items in Inigo's inventory.

It must (obviously) be placed after Inigo in your load order.


Credit:

Thank you very much to hairahcaz for the idea for the solution to this tenacious and insidious problem, and for his insight into, and astute observations about, the guts of things like SKSE64 and obscure faction settings.  I would NOT have figured that out on my own.

To Smartbluecat, of course, for creating Inigo.


Likely questions and answers (FAQ):

Q: Can't you just include this in the Inigo SE main esp?
A: Yes, we could, but we aren't going to go altering the main esp when it has only been confirmed to work by one tester so far.  If it proves to work and be safe, as we think it will, we will be integrating it into the main Inigo version eventually.

Q: Why isn't this just added to the files on the main Inigo SE page?
A: As this requires some further testing, it is much easier to keep track of the responses and questions that pertain to only this on its own page.  If it was on the Inigo page, questions, problems, and reports would be mixed in with all the usual Inigo stuff, and be much harder to separate out.

Q: Can I merge this with something?  I need every single esp slot!
A: There is a good chance that after testing, it will be merged with the main Inigo.esp, and the separate patch will no longer be necessary, so merging it with anything would probably be jumping the gun, however Rynfri provided an ESPFE (ESL flag turned on) version before I could even get to it, so using that instead should alleviate your problem.  See optional files.

Q: I am on XBox, do I need this??
A: Do you use SKSE64?  I thought not.  So no, you don't need this, though it wouldn't hurt anything either.

Q: I am using Skyrim AE, do I need this??
A: If you use SKSE64, then yes, you do need this.  A tester has confirmed that the riding problem still occurs when using Skyrim AE, and the SKSE64 and Racemenu versions meant for AE.

Q: I have been using Inigo already in this playthrough, can I use this?
A: If you have not taken any of Inigo's starting items from him via the trade menu, and have not given him a horse yet, then yes, you can.  If you have taken some of those items from him, even if you have not yet given him a horse (or vice-versa), you might have already pre-triggered the bug.  It should not harm anything to install this after triggering the problem, but this will not fix the problem once it has been triggered, even if you had not yet given Inigo a horse, so were unaware that the problem had been triggered.

Q: I want to use this, but I don't want to help with testing, as I am not going to be getting a horse for a while yet.  Can I use this and not help with testing?
A: Of course you can.
The more people who test this, and report the results to us, the faster this will be integrated into the Inigo main file if all is well, but I fully expect quite a few people to just install it and forget about it, particularly those starting a new playthrough, as that is when it is most effective.


Potential Mod Conflicts:
None that I can imagine.

Okay, that was a failure of imagination...
Any mods that alter Inigo's appearance, such as Inigo the Suave and HP Inigo, will need to be updated with these changes, as otherwise either this patch will overwrite their changes, or their mod will override these changes, and the riding problem will still be in effect.

Also, any mod or patch, like the one for Morrowloot with Inigo, that changes his starting items, or in any other way edits his NPC record will also have to be updated to incorporate these changes.

Anyone who uses such a mod or patch, please alert the author of it about the need to integrate this patch.  I can not keep track of them all.