Could we have the converted assets made as components and not groups and also have the scale applied to it (select sketchup component >right-click>scale definition) ? All the time it’s the first thing I do in sketchup.
If you want to use it with skatter you have to do those steps otherwise you have very small instances and need to crank up the scale to 5000.
The *.skp file generated by Transmutr is intended to be imported as a component in another model. Do not open it directly.
Please try that and report if you still have the same issue.