I am having this problem in a model I “picked up” form others. The model already had some cross sections with multiple obstructions.
I needed to add a second obstruction to a particular cross-section that already had an obstruction. The original obstruction was previously input using the “Multiple Blocks” radio button, so there was no issue there. (My new obstruction was in the right overbank, near the original obstruction.)
When I tried to add the second obstruction, I got the error message you guys described. I did not save the geometry file at this point, but simply exited the program without saving anything.
I re-opened the project and selected the plan in question, then opened the geometry file, which was in its original state with only the one original obstruction at my cross section. I deleted the obstruction and saved the file, then exited the program.
I then re-opened the project/plan/geometry file, which now had no obstruction at my cross section. I then added both obstructions (the original and my new one) using the Multiple Blocks option, and it worked! I saved my file and ran my model successfully.
Just thought I would verify for everyone that this fix does work. I’d still like to see this bug squashed in the next release…