Yeah, pieces be missing after this update. Or just invisible rather. Removing the mod fixes the issue.

Ditto. Particularly floors from various mods (LBPR, Dude, Erebus Gothic, Desert Town). Present but invisible. I load Ancient Architecture after those (except LBPR per instructions), because I generally load in reverse order of favorite sets and I really like this one. I have also previously experienced the bug regularly where fortress floors have no collision (you can pass through them). Fantastic content. I don't want to rain on this parade at all. Just corroborating the issues.

If it's any hint ... I first noticed the issue with Erebus Gothic floors.

1. Updated this mod.
2. Started game (solo).
3. Noticed Erebus Gothic floors in some positions were invisible.
4. Thought it might be a conflict in particular with the weird technique E.G. uses where if you rotate a tile you get a different look. I load E.G. before other build sets because although I like it it is my least essential. I load A.A. late in my build sets because I like it most.
5. Replaced the E.G. floors with Dude floors (Castle 1).
6. That only helped temporarily. Next start those were invisible too.
7. Later noticed LBPR Tavern floor (I mean ceiling) elements invisible.
8. And then Desert Town's stick ceilings.

etc.

Replacement with Bossonian (Northern Timber) or Notch and Arrow (Shima's Compendium) seem to be reliably visible. Maybe. I load all my build sets before A.A. except LBPR and PEB.

Another maybe hint ....

Presently NO ceiling previews show up in my game. All are invisible no matter what build set. The ones that are visible when placed are not visible UNTIL placed.

I Placed Ancient Architecture at the top of my modlist and problem is gone

So I have been activelly using this mod since 3 weeks now. I love this mod and building design. I have had zero issues loading it