I'm not sure if this is a problem in xUnit or pipeline multibranch plugin. Please reassign this as required.
We've got a Multibranch Pipeline project and we upload various test results using the xUnit plugin. It's somewhat like this:
The trend chart shows up when builds fail with or without tests or succeed with tests, but the chart disappears when the build skips stages which record the tests. To be entirely honest, I'm not sure what the current behavior is exactly (it's inconsistent).
This should be fixed. As long as there are test results in any builds at all, they should be displayed regardless of test results in the latest build.