Manual Forecast entry being set to Inactive

What parameters is MRP using to determine whether to set a manually entered Forecast record to Inactive?

We created dozen manual Forecast records a couple months ago, in anticipation of some new items we were setting up. These had no attached sales orders, no existing work orders or even min/max/safety numbers set. These parts had zero demand and zero supply, other than the forecast records created
The last of these manually created forecasts was dated 7/27.

After MRP ran last night (7/13) this 7/27 Forecast now shows as Inactive.

Forecast window is Days before 0, Days after 7
The item is set with a Transfer source on the site used when creating the Forecast record, TO lead time of 2 days .
The demand is dated 7/27, and last night’s MRP set it to inactive.

Looking through the BOM, I can see a couple of these items are source Purchased, but have no lead time and no set supplier at Part/Site level.
I also see that at least one item on the BOM that is “use revision” but has no approved revision.
I also see some materials on the BOM that are Transfer source, and have long lead times.
All of these seem like good reasons, and I’ll get them cleaned up, but I was wondering if it was something else, something I’m missing.

What all reasons cause a manual forecast entry to be set as Inactive?
I don’t see the question addressed specifically in the MRP tech ref. Is there a Forecasting tech ref?

Thank you for any help