"Mourning Never Comes" Quest Start Broken

[Milepen]

Hello, boys and girls.

I've been googling for solutions to this thing for a couple of weeks now to no avail. But to err is human, so if somebody manages to throw a very efficient search result at me, I apologize for wasting your time. But onto the matter at hand in question.

I can't start the Dark Brotherhood quest "Mourning Never Comes". I would like to be able to start it without having to start a new character.

More specifically, the initial trigger of having Cicero show up at the Sanctuary never happens, or that is to say he never shows up. From what I understand, as soon as you've completed at least one of Nazir's initial contracts, returning to the Sanctuary should trigger a scene with Cicero there. But no matter how many times I return to the Sanctuary, nothing has happened and Astrid keeps telling me she has no primary contract for me yet.

So, some background info. I did the pre-DB quest to help Cicero near Loreius Farm ("Delayed Burial"). Once I joined DB and got Nazir's contract, I did all of them in one go before returning to the Sanctuary to report. And once I returned to the Sanctuary after that, expecting to see Cicero, I got nothing. Astrid won't give me no quest no nothing whatsoever.

I tried to jump-start the questline back on track by using console commands to start "Mourning..." and proceeded to complete it, but Cicero never showed up and I was stuck again, so I went back to an earlier save before I used the console commands. To check things out, I also started a new save, beelined for the Brotherhood and was in fact able to start "Mourning...", jesters present and all.

Possible mod conflicts? Uh, probably? I have a metric buttload of mods, but nothing that specifically targets anything DB-related. And like I said, a new save (still running those mods) let me start the quest no problem. What I imagine could be the cause is the Unofficial Skyrim Patch. I started off playing with it, but uninstalled it halfway through after I discovered a severe conflict with Dragonborn DLC (in short it prevented any and all Dragon Soul absorbing).

I've kept it uninstalled since, and started the Brotherhood questline after the uninstall. The aforementioned new test-purpose save still had it uninstalled. I also tried to see if reinstalling the mod would let me start the quest (in the broken save), but nothing happened. Also, I run all my mods through the Nexus Mod Manager.

So yeah, that's a lot of info. So for clarity's sake, my issue is that I can't trigger the start of the Dark Brotherhood quest "Mourning Never Comes". I'm trying to see if anyone has a way of getting me back on track without having to start a new character. The whole point of this one is to be my obsessive-compulsive do-everything save. I don't relish the prospect of starting over. If you all think that a mod might be the culprit I can provide the complete list of mods I'm running. But there's nothing particularly invasive or Dark Brotherhood-related, save for the Unofficial Patches which tend to be pretty far-reaching.

Many, many thanks in advance. I appreciate any help I get.

Best regards,