Hi,

      Since the clients are managed they will communicate with the SEPM Symantec Endpoint Manager at the default time interval of five minutes(unless you have chaged the settings) this is commonly known as the heart beat interval. To further narrow down on what dependency can cause this issue please follow the steps below and let us know whether it helped.

1. Open the Symantec Endpoint Protection Manager.
2. Select Policies from the far left.
3. Highlight Antivirus and Antispyware under the View Policies section in the middle column.
4. Highlight the active policy from the right side of the manager.
5. Click Edit the Policy under the Tasks menu is the middle column.
6. A new window will open.
7. Select Administrator-defined Scans from the far left menu in the new window.
8. Select the Advanced tab.
9. From under Startup and Triggered Scans uncheck Run startup scans when users log on and Run an active scan when new definitions arrive.

When you configure Auto-Protect options, you can click the lock icon next
to the Auto-Protect settings. Users with the client computers that use this policy
cannot change the locked settings

File System Auto-Protect uses a file cache so that it remembers the clean files
from the last scan. The file cache persists across startups. If the client computer
shuts down and restarts, File System Auto-Protect remembers the clean files and
does not scan them.
File System Auto-Protect rescans the files in the following situations:
■ The client computer downloads new definitions.
■ Auto-Protect detects that the files might have changed when Auto-Protect
was not running.
You can disable the file cache if you always want Auto-Protect to scan every file.
If you disable the file cache, you might impact the performance of your client
computers.
You can also set the following parameters:
■ The file cache size
The default cache size is 10,000 files per volume. You can change the cache
size if you want File System Auto-Protect to rescan more or fewer files.
■ Whether or not Auto-Protect rescans the cache when new definitions load
You might want to disable this parameter to improve File System Auto-Protect
performance