Hello,
Need some help here:
Im trying to collect ceiling elements for all linked revit file. Few hours back, it was working, suddenly showing empty.
Im using dynamo 2.0.3 and Packages: steam nodes, bottom is synthesize and bakery
Any help is appreciated. 
Is it still not working? A restart sometimes helps restore the order. 
@jacob.small thanks Jacob
In evening it worked. 
I couldnt understand what had happened!! Is it my pc’s fault?
Yes.
And no.
It’s impossible to know without a LOT of digging, and even with it we might not find the smoking gun. Basically when this happens Dynamo has entered a bad state (so Dynamo’s fault). The reason for that bad state could be a nearly limitless number of things, including a issues with Dynamo (memory leaks a common one), issues with the host program (Revit does Revit things sometimes), or issues with another system setting (pull up task manager, go to the details tab, force quit a random process and evaluate how your stuff runs, repeat the process until there is a shutdown or a crash), or it could be user error (not saying it’s likely but everyone does something silly like acidentally changing the active doc).
In any case there is a lot of effort underway to fix as many of these kind of issues as possible. For now just add ‘restart Dynamo’s host application’ to the list of troubleshooting steps you use.
Thanks @jacob.small I never knew it had such issues 
Hope it will get resolved in coming versions.
How can I give this as feedback for improvisation to dynamo developers?
Feedback can be given on the GitHub. There is also a Twitter thread discussing some other fixes that are underway, and between myself and the many developers who check the forum most messages here get passed on one way or another. It’s part of the reason I try and read every topic - well the first posts anyways.
That’s Awesome Jacob!
