The displayed jobs in our build queue are changing in 10-second interval.

Jobs are disappearing from the build queue and after some seconds they are visible again (jobs were not executed, so it has to be a GUI bug).
The number of jobs in the build queue is jumping in a big range, in one second it could be 8 jobs, next second 0 jobs and in the next moment over 100 jobs and back to 22 jobs, etc.

We are using the Jenkins version 1.642.2