So, after installing Hearthfire I created a new playthrough. I finally got around to purchasing the lands in each relative hold last night. At that point, all the new Hearthfire content had been working fine - adoption, kids' bedrooms, misc. items, etc., with the exception of Honeyside's (Riften) basemant room being glitched (can't purchase enchanter's room/kids' room which I read off of the UESP that it's related to the garden).

However, all 3 of the houses are invisible. The misc. construction items work fine, it's just the house itself that's the problem. Each lot is fully equipped with smelters, workbenches, grindingstones, and so on, but no house.

From lots of google and forum searches, I understand that there are known mod conflicts. The issue is, I don't have any of those mods. Any help is appreciated.

My current mod list:
Unofficial Skyrim (1.2.2)
Unofficial Dawnguard
Unofficial Hearthfire
Daedric Extra Armor (Lustriannas Daedric Armor - Heavy UNP)
Elegant Vampire Armor
hothtrooper44 Armor Compilation
Female Werewolf
The Eyes of Beauty
MacKom Lore Styles Hair Set
Nightingale Arrows
Vampire Lord Serana Fixed
Babette.esp

And a plethora of HD textures which I'm assuming isn't causing this particular issue. Also, I've tried disabling all mods, and going through disabling 1 at a time, but no luck. This issue is really maddening.

Having the same problems... I use only a very few o the same mods... the unofficial patches and hothtrooper44 Armor Compilation.
There are some other mods which are known to cause this problem...

- Eindeutige Regionsnamen from SDC in the Version 2.1
- Birds and Flocks
- Distant Details

however, I had disabled all of them and still got the issue. I think there are a lot more mods out there with compatibility problems with Hearthfire than we already know of (even mods where it doesn't make any logical sense content wise). Best thing to try is disable all mods and check and then enable them one by one

Yeah, I'm also assuming the same. For now, though, I've just done a clean reinstall and restart of the game without mods. I'll slowly reintroduce my mods to see if I can level it down. The houses do show up on the clean reinstall, of course.

The texture packs might be the cause of the issue? I don't know what you are using. Unless it is the official DLC High Resolution Texture that you can get thru steam. I have that one installed and I am not having any issues.

These Houses aren't there, with or without texturepacks... you can walk thorugh... seems to me more like the meshes didn't get enabled in the first place at all...