Extract block selectors fails when dash is in selector name

I am trying to debug a rather difficult issue in 5.10.1 when using ExtractBlock on an OpenFOAM dataset.

In previous versions, extractBlock worked very reliably by setting the BlockIndices to extract. However, I am finding unstable, inconsistent behavior with the new “Selectors” method.

I am using a python script to extract all blocks starting with w, but this fails when there is a dash in the name. So the scripts executes:

extractBlockFilter.Selectors = [’/Root/boundary/w_l_body-dash’, ‘/Root/boundary/w_l_body_medium’]

But w_body-dash is NOT extracted. When I generate a python trace in the GUI, it works, and it says:

So it seems there is a bug in the Selector itself? Any ideas on how to work around this? Why was the block indices method dropped?