Is the floor still tacky or not does look like it fully cured?
There can be a variety of reasons why the epoxy has not cured.
1. The epoxy was not mixed evenly which can cause chemical imbalances in the curing compounds.
2. There could be moisture in the floor
3. The floor was not prepped the correct way
For the area that is not fully dried we would recommend scraping up that area. Use can use some paint thinner like xylene to assist in getting the uncured coating up. Then once dry do some light prep with the sanding paper. Make sure to vacuum or wipe down the area with some denatured alcohol so there is no residual dirt debris left behind and you are ready to re coat. Wait a full 24 hours before applying the top coat to ensure that the epoxy has fully cured.