Tried all troubleshooting steps and then some. Import just hangs

I did everything the troubleshooting and support forum posts said: memory boost to 256M, max_execution time raised, PHP versions aligned, WP versions the same, deactivated EVERY plugin – free and licensed before export, broke up my exports into chunks, tried new browsers after 15 minutes and resaved permalinks…NOTHING WORKS. It just will not import. I even paid for the Unlimited addon too. The imports hang, then say “Unable to upload” over and over again. Also, using different hosts makes NO difference. I used to use this plugin with success, but now it’s a total waste of time.