Import Main Demo does not complete

We’ve increased the memory limit.
We’ve increased the PHP execution time.
We’ve install all required and recommended plug-ins.
(we’ve tested deactivating all plug-in’s per one posted solution)
We’ve reset the database and started completely over, twice.
We’ve tested other demo imports.
We’ve even attempted the manual demo import.

The recommended import function has been churning and asking us to
“Please be patient while Highend Main Demo demo is being imported. This may take a few minutes.”
for over 8 hours now.

Please advise.