The sticky spots are most typically uncured resin or hardener which hasn't been completely mixed in. If it's excess resin it can be removed with a strong solvent like lacquer thinner. If it's excess hardener it can be removed with soap and water. The sticky spots can be either, or both. Both clean up methods might need to be used.
The voids can be filled with small quantities of newly-mixed Mirrorcoat, carefully using a spatula or squeegee to smooth out any excess material. Let this cure 24-hours and lightly sand the surface with medium-coarse sandpaper. Finally, apply an additional flood coat at 4 fluid ounces per square foot.