Ragdoll opens, but GUI doesn't show

I’m using the Trial right now and the plugin appears to be running, but when importing one of the default characters and choosing the manipulator tool, I’m not seeing the GUI in the viewport or any of the markers in the viewport. I’m seeing this in the script editor:

ragdoll._create_solvers() - Creating solver(s)…

Error: Failed to create evaluator for “drawdb/geometry/rdSolver” classification because the current drawing API isn’t supported.

Any ideas?

See The current drawing API isn't supported