S-curve "Late start"

The width of your s-curve envelope reflects the amount of float your project has. Obviously, your project has lost a lot of its float. Did you impose a constraint to project completion? Did you forget to status a critical activity?

You should be using the s-curve envelope from your last approved baseline schedule to use as a reference, not the current one based upon the current float. Either way, it appears that your project is in trouble, assuming that you have statused it correctly. Good luck!

Do you use a target plan? If so, you should have the same early and late curves all the time.

If you actual now drops below your late, you have a serious problem on your hands and you need to investigate what went wrong.

If you are using a target plan and your late curve is changing, check you early curve too. Is that changed? Then chances are you or someone made changes to the target project (should never be done).

If you have a target, never changed the target and just progress your current plan, check your curve report and make sure that the target plan always goes to 100%.

Did you delete resources from your current plan, making your actual curve drop?

So many things you should check, so many things that might be wrong here.

Give us some more info and we might be able to help you better.