can you immediately apply a coat of joint compound over the tape?
It should be done separately, set tape first let it dry, then the build up coat, let that dry, then final skim. If you do the build up coat immediately after setting the tape, the shrinkage will be enough where the skim coat will not fill the depression left by the excessive shrinkage of the 2 coats applied together.

I have gotten past this by using a fast setting joint compound that is dry in the package and mixed with water. Not only can you do tape and do the buld up coat, shrinkage is less than regular ready mixed joint compound.