Packaging project, endless "missing cached shader map"

Hi, I am trying to package my project for a test version, but I have hit a snag.

As the package builds it has to compile the shaders, it takes a while, but fine.
But as it finally gets to zero, I get this error with my landscape material: “missing cached shader map, compiling.”
Then it repeats, over and over and over for probably about a 100 times, adding more and more to the queue of materials needed to be compiling in the tens of thousands.
And when it finally stops, I get the same error for all the other materials in my project, and on and on the loop goes.

What’s going on and how do I solve it?

I got the same here. Have you every found it out?