At the very top of the Auctiva one-page lister under Sale Type, select "Store Item" for your ebay store inventory items. That will switch the lister's mode to give Durations of 30 Day or GTC (Good 'Til Cancelled).
The lister has custom selections for each of the three modes: Auction, Fixed-Price (Floor BIN), and Store Item (Store Inventory BIN). Note, my distinctions for purpose on the last two. The last is obviously only for an eBay STORE SUBSCRIBER. The first two follow 10 day or less rules and fees.
Tips:
When using the lister, it's usually best to select the "Maximize All" at the top to unhide all the features and options.
Use the Error Check at the bottom to catch any obvious errors before you list or save. Note, the errors appear at the top of the page.
Also, use the Estimate eBay Fees to double-check what you think you're listing and how to see if it matches what you know should be correct fees. That is a good sanity check that will stop (or reduce) those listing error problems of quantity and/or Store vs. general listing mistakes (most of the time).
Danno