New Code Coverage has been gone and show as --

Hi All
Regard to sonar project build, we do the below steps:

  1. build one version(3.40.1-SNAPSHOT 8th May) as base line and the next build will compare to it.
    2.All of our subsequent builds will use the same version(3.42.2-SNAPSHOT) and will compare to 3.40.1-SNAPSHOT, our code will be always change and we’re still add the test for improve code coverage, so coverage on new code should always have value.

the coverage on new code is always have value before, but it’s gone and show as “–” after our newest build:

could someone please help me check this issue? the coverage on new code should not be null.