QVTKWidget shows up as transparent

[stephensunyj]

Hi, I have been trying to set up the cloud_annotation_tool. I have successfully compiled and built the program, but when I open it, the QVTKWidget that should be displaying the point cloud is completely transparent, and shows the windows underneath it. No error messages are printed in terminal when I run the tool. I have tried numerous rebuilds. It is strange because pcl_viewer seems to work fine in a separate window, and running the PCL visualizer code https://pcl.readthedocs.io/projects/tutorials/en/latest/pcl_visualizer.html#pcl-visualizer also seems to work fine by itself.

Has anyone encountered this issue before? Any help will be appreciated. Thank you.