This might come from something like Hops that’s spinning up new Rhino processes in the background. I’m not sure if there’s a way to force Hops to use .NET Framework, if that’s the culprit (meaning you probably can’t use Tekla components in a Hops sub-definition).
Thank you so much for your quick and helpful response! You were absolutely right — the issue was caused by the Hops component. After removing Hops from Rhino, the Grasshopper–Tekla live link started working without any errors.