Thought I'd post the answer to my question. Yes, the fix was
right in front of my face. The more I thought about it, the more I
realized this couldn't be a RoboHelp issue because it worked
correctly calling the path. The answer did lie in adding the .fhs
mime to iis. Unfortunately the first try didn't work, but on a
second attempt it came up perfectly.
On a side note, thank you to Rick Stone & Peter Grainge
for all the great information, tips/tricks, and everything else you
both have contributed! It has been very helpful!