It's possible that the forecast for the affected products is not being calculated correctly due to some specific settings or configurations in your Odoo system. Here are some possible reasons and solutions: 
Incorrect inventory valuation, Incorrect replenishment settings, Incorrect sales and purchase history or
Forecast settings

If none of the above solutions work, you may want to consider seeking assistance from an Odoo consultant like silentinfotech.com to help you diagnose and resolve the issue.