Here is another potential fix to your problem. Please let us know if you're still having trouble.
Thank you for the input on the possible reasons why I am unable to create an extract.
A little insight into the environment and then the solution I stumbled upon:
We are tying item movement (by day, by store, for 2 years) to the Item file where a UPC is the primary key. Item table has over 200 fields, 150k items, and the item movement table has about 20 fields and at least 10k records per day per store.
The solution was to connect live to build the initial connection, then go to the Item table and hide any fields that were not going to be used (which hadn't occurred to me because I'm new to this whole thing) which got me down to pulling only 4 fields from the item table. An extract created very quickly in this manner.
Thanks for the quick responses!