I think I managed to reproduce the issue and found a fix for it.
I’m releasing version 2.6.3 to address this (and an even bigger issue) for all connectors.
Should be hitting your Speckle Manager sometime this morning 
Let me know if that does the trick!
The error I was getting was about a null reference in the BeforeSolveInstance method of DSO.
I’ve also added some safeguards so that if this (or anything similar) happens, you should get a more informative message from the node.
Thanks again for taking your time to report it, and for the patience while we fix these things.