Magical dissappearing prim

I'm building a new building on a large lot.

Everything was going fine until I noticed the corners on my building kept dissappearing.

The way it's set up, it uses thick walls, 0.5 meters thick, with a 0.5 meter snap to grid. I don't fully overlap the corners, so I'm left with a 0.25 square gap on each edge. I fill those with cylinder prims to make a smooth curve.

Everything worked fine with that plan until I got to the corners. I rezzed half-spheres and dropped them in place and they looked perfect. Then 5 or 10 minutes later I noticed they were gone!

Put new ones in and same thing happened. They aren't temporary on rez, and they are definitely within my property lines. This is really driving me crazy. Any help appreciated.

Now they are back. They completely weren't there, and now they are back. So weird.

All of them are back in fact. I'm dragging off all the layers of replacement corners.

This happens because the SL client tries to optimize performance by dropping smaller objects at a distance. The objects are on the server, but they just aren't displayed by the client.

This has always been the case, but it seems that recent changes may have made the problem worse.

In any event, the best solution is probably to link the smaller disappearing prims with larger prims and make sure that a large prim is the root of the set. This should prevent them from disappearing.

I'll try that. I guess it was an artifact of sitting on one side of the lot and pulling the camera over to the other side to edit things.

My camera was close to the prim, right on top of it, but I wasn't, I was pretty far away.