Greetings, I have the same problem
I have installed the latest version 2.18 for Archicad and I get that error. “Can’t start Speckle UI”
as additional information. I am a Spanish speaker and I have 27 degrees in Spanish.
In my extensions manager I verify that I already have the addon installed.
I hope you can help me.
resolved: I have manually created a folder with the name “speckle” in the “extensions” directory of archicad 27 (Spanish) and inside I have copied the speckle APX. I restarted the PC and the interface started.
Thanks for sharing how you solved it @jonabatero . We encourage you to share how you are using Speckle. Don’t hesitate to ask for help if you have any other queries.