Hmmm, then unfortunately a combo of file size and limited network bandwidth (internet speed) might be the problem. That file size equates to 6,000 MB, or 48,000 Mb, although when factoring network overhead it might look more like 60,000 Mb. Without a pretty fast internet connection the upload would take a very long time which could exceed the maximum time for an allowed transaction with AGOL. It's a pain because 6 GB doesn't seem all that large, but in this case the internet connection bandwidth could be a choke point in the "performance chain."
Any chance you could split it up into smaller chunks and upload them individually? You might be able to create a fishnet layer and use the extent of the resulting squares in the extent parameter of the create tile package tool. Just an idea.
Any Esri AGOL staff folks want to weigh in?