First is hardcopy generation. For a given assignment, if I click "Generate Hardcopy", nothing seems to happen: it simply gives the message (after ~ 4 seconds) "WeBWorK was unable to generate a paper copy of this homework set. Please inform your instructor."
I went through the Troubleshooting Hardcopy wiki, enabled PreserveTempFiles, and checked to make sure that: a) pdflatex is working (it is), and b) that the configuration for WeBWorK points to the correct binaries (it does). But nothing shows up in the /html/tmp/ directory at all: it's like it isn't even getting that far.
Suggestions for what to try are quite welcome. I feel like I'm debugging blind, so I'm at a loss as to how to proceed, with no temporary files and no output, but a clear failure to execute.