All of a sudden since when? When did it last work for you?
I don’t have the TF extensions installed but I just downloaded the components and extracted the one called Spline 32 which I opened in SketchUp 2026. I see this:
Looks like a pretty trivial thing to model if you had to do it.
Perhaps you have the tag called Main turned off or you have another issue with your tags. Turning the tag off would leave the bounding box if the thing is selected.
It is trivial to create the model but you have to set it up properly so that is ‘cuts’ the adjacent timbers correctly as well as registering the peg holes when you create shop drawings.
I don’t use the joinery aspect of the TFRubies but was versed in them 10 years ago.