Hi there
While I can't explain why (maybe it's the phase of the moon?
Sunspots?) I can tell you it's happened to me in the past. At the
time it happened to me, I attributed it (correctly or incorrectly)
to either my path being too long (I had many nested folders) or too
many drop-down areas inside a single topic. (I had 25 or 30
different areas).
Whatever the cause, mine began working when I changed the
path to the ehlpdhtm.js file. I removed all ../../../ information
and just copied the file to the same folder as the topic that
needed it.
Not sure if it helps any, but that's been my experience.
Cheers... Rick