When looking at Content Status of distribution points, you may see a warning status with the following message: Failed to retrieve the package list on the distribution point. Or the package list in content library doesn't match the one in WMI. Review smsdpmon.log for more information about this failure.
This because of a mismatch between the ConfigMgr content library and WMI. You can enable content verification, but after a while the warnings are still there. There is however a solution available, but not default in the ConfigMgr console. Let's have a look at it.
When looking in smsdpmon.log you will see the packages which are out-of-sync or doesn't exist anymore. When having multiple distribution points, there may be different issues as well.
In my case I started a PowerShell script, which can be found here: windows-noob.com
After running the script from Peter33 and start content validation some days later, the issue was gone. Hope it helps!