BO Promotion management jobs stuck in pending state

Dear experts,

We have a issue in a standalone environment (BO 4.1 SP6 Patch3).

Most of the time, the jobs stuck in pending state in promotion management. To fix this, we always have to restart adpative job server (AJS). It runs fine for sometime and again we start noticing the issue after sometime.

Do not see any logs or anything in event viewer. Also we did repair the installation but this didn't helped.

Any clue on this?

Thanks in advance.