Casas Probas disaster?

[Donnerna]

Hi all!  I found a major error in one of my cities, where empty residential lots would get construction (IE a new house being built)...but that new lot would be nothing more than a dirt or paved lot.  No buildings, no props, just flat dirt or cement (occasionally with a driveway, but no car).  Other lots (mostly commercial) that were already successfully built suddenly...lost their flooring?  The grass, cement, whatever around the building would suddenly become like the border around the whole city. 

Is that making sense?  I'm worried it isn't.

Anyhow, I figured I must have failed to download a dependency...I eventually deleted my entire download collection and started over from scratch.  I took specific care to download every dependency, etc...and it's happened again!

When I click the grass/pavement residential lots, they say "Casas probas".  I can't figure out which download that applies to.

Can anyone help?

Thanks so much!

EDIT: I was going to post pics, but I don't know how to make a png into a jpeg.

[Donnerna]

More info:  I'm having the exact same problem on lots titled "Atzingo" and "Pab 1x3".  Does anyone know which download any of these houses came from?

[Donnerna]

Figured it out!  It was the LBT houses...I missed a dependency.  Thanks!