Multiple Items with spiked forecast value compared to shipment history

Summary:

Multiple Items with spiked forecast value compared to shipment history

Content (please ensure you mask any confidential information):

There are thousands of items in the demand plan and only one item was found to have a forecast value much higher than its shipment history. Shipment history month to month is between 1 and 8 where as the forecast is approximately 87 month to month.

Also I have noticed, the more I run the plan, the Forecast value becomes better.

Need to understand how to get the accurate Forecast value in such cases.

Version (include the version you are using, if applicable):
24D