Suddenly, Objects With Screen Door Fade Not Showing Up

[Lacabra]

I've been using July 2012 UDK since the day after it came out, no problems, and I've been working a lot, so presumably I changed something to cause the problems I've been having since last night.

Basically, I opened the editor last night and a bunch of stuff appeared to be missing from my maps, but it shows up on the Lighting Only viewmode. Certain things flicker on and off as I fly around in the editor. Pics below.


Lighting Only:

Lit:

Unlit:

Wireframe (even here, the foliage is visible again, but the rocks in the background aren't):


It seems all of the affected objects are using materials with bUsedWithScreenDoorFade True (so that foliage can fade out, and objects can switch LODs reasonably smoothly). If I disable it, the objects become visible again.

This is only affecting maps containing my content - if I open the foliage showcase map, everything seems fine (that map does use a lot of screendoorfade-enabled materials, curiously enough) - but the content has not been modified since before this started happening.

For kicks I pasted one of the affected meshes into VCTF-Necropolis. Unlit, it's completely invisible. Lighting only, it looks fine. Lit, it looks like this:

Until I disable screendoorfade, at which point it's fine:


It's tempting to just say "Whatevs, July broke screendoorfade, I guess!" But I was definitely using it yesterday with no problems at all, and the foliage map's fine.

I've also tried swapping out all my config files with unaltered ones from a fresh install, no dice there. Anyone encountered this before, or have any idea how I might have broken it?

Edit: Just found out by zooming in and out a lot that this is only affecting meshes that have both bUsedWithScreenDoorFade and multiple LODs, and if I zoom in and out a lot the meshes will appear for the ~1 second duration of the screen door fade, then disappear again.