debugging a "never finished" function

I recently moved my webjobs + scripthost setup to an Azure Function app. This transition was fairly smooth.

Last night, I finally made the swap from my staging slot to production. Unfortunately, a number of my functions runs went into a "never finished" state with a 0ms run time. There is nothing that I can see in the logs to make any sort of diagnosis.

What typically causes a function to enter this state? How best to debug it?

Thank you!

The report names no source files or tests; begin by examining Azure Function runs that show “never finished” with 0ms and compare staging and production logs after the slot swap. Done would be a reproducible cause and a documented debugging path.

Written by the indexing model from the issue text.