Hi Dan, still a problem in 29Aug17 WIP. I’ve experimented a bit more with this and I think you should be able to repeat the behaviour with the following. As @3dsynergy said, it’s a pretty big problem.
BM Worksession C.3dm (62.2 KB)
BM Worksession D.3dm (40.0 KB)
After attaching and detaching a worksession using the steps in my previous post, this is what appears to be happening. Follow the steps in the previous post with these files C and D to repeat the behaviour.
File C screenshot
File C with file D worksession attached.
File C after detaching and rebooting Rhino.
On the re-opened file C there are additonal rogue layers added to the top of the layer table, yet the original layer order remains, so the geometry all shuffles up the list filling the new layers.
The number of layers added corresponds with the number of layers in the attached worksession, so if the open file has many layers and the worksession has just a few, then the added rogue layers will populate with geometry from the corresponding no of original layers. All the remaining geometry in the file layers will jump up the list and the file becomes a huge mess.
It appears that the geometry on the default layer remains intact if the worksession has the same named layer current.
I also noticed the file survives if there are multiple Rhinos open and the worksession one is not the last to shut down.
In the meantime @3dsynergy beware of V6 worksessions until fixed, bad for your health to open a file in the morning that has been decimated… especially with a deadline. Thinking about this a bit more, you can correct the file by selecting by layer and placing the geometry back where it should be - might take a couple of hours but you get the file back in a working state.