Mass created by Dynamo cannot be selected

Hi everyone, I am using dynamo to create mass from rooms. After I created the mass, some can be selected but some cannot. How to fix this? Here are the dynamo file, model file, and screenshot. Thank you!

room_to_mass.dyn (28.9 KB) https://drive.google.com/open?id=1E2o4S4267liEqwgvrENBCYijkD8n_wOL

For the ones which cannot be selected you are only seeing the background preview. Look closely at the lacing for the node You are using which creates the mass.

Hi JacobSmall, thanks very much for the reply and it worked. I checked the lacing of the node used to create the mass and found that it is auto. And I also found that when it was auto, the no. of mass was less than the no. of rooms and some could not be selected. I set it as longest then the results are right now. The no. of mass is the same as the no. of rooms and all of the masses can be selected. Do you know the reasons behind it?

Auto lacing defaults to ‘shortest list’, reusing single items (if they are nto in a list) for longest lacing accordingly.

Look into the Dynamo Primer section 6 for a description of what shortest/longest/cross product lacing is. What's a List | The Dynamo Primer

Reviewing each exercise on that page is worthwhile for anyone getting started with dynamo - skip nothing even if you don’t think you’ll ever need the result, as the exercises are designed with the methods in mind not the outcomes.

OK! Thank you!