Tough to say from this information without digging into this in more detail. Sounds like this could be related to the overall process or the process of seeding Actuals to Forecast ( i.e. data copy through DM or seeding from a Business Rule ) after data is already submitted in Forecast Scenario. If using a Business Rule to seed, there may be something in the formula that needs to be addressed. I would suggest submitting a support ticket and spending time with AAS to review this entire process.
If you use a business rule for the copy and if the forecast is loaded and/or manual input, then you need to actively delete the data before the override. The clear function can’t easily delete data that isn‘t calculated (but there is an answered OneComunity question discussing the topic).
