Active listings are listings that are found on the Manage Listings page of LM. LM is in full control of active listings, meaning it is syncing out QTY and listing data (non-Amazon) to it. It also allows LM to use the active listing as a base for creating listings on other marketplaces.
Inactive listings are found on the specific listing page for the channel they exist on, with a little plug icon above the thumbnail image. LM does NOT control QTY or listing data for these listings. Nor will you be able to use them to create other listings. This is normal for newly imported listings.
Right on top of your channel listings page, you will find a banner that tells you how many inactive listings you have. It will also ask you to activate them, or enable Automatic Activate.
There will also be a red icon on top of the channel on your Manage listings page, which shows you the number of inactive listings on that channel.