Nodule activity is sacrificed. If soil pores are filled with water, not air, there is no N to fix. If there is no air, there is no N to fix. Using inoculants N-fixing bacteria are fragile organisms. Inoculants need to be handled with care.
Proper storage is critical.
Make certain the inoculant is fresh and has been stored in a manner recommended by the manufacturer. Inoculation ahead of seeding is possible, but check with the manufacturer to see if the shelf life of the product will allow it. Some seed treatments are toxic to inoculum. Captan and PCNB are very toxic to inoculum. Vitavax is relatively safe up to 24 hours before seeding.