With Mayavi installed through Conda, running the following script in a Jupyter Notebook:

%gui qt
from mayavi import mlab
mlab.test_flow()

then clicking in the GUI to save the scene, if I set the file output as "snapshot.pdf", I get an error message in the terminal that opened the notebook:

2016-06-21 12:03:43.383 python[44385:6652218] modalSession has been exited prematurely - check for a reentrant call to endModalSession:

and no PDF file is created - a file called snapshot.pdf.gz is left.

The environment I'm working in his here:
env.txt