Scope of "Exclude content not linked directly or..."

[Bea Lac]

I would like to use the new option in 7.1 version in the Target: "Exclude content not linked directly or indirectly from the target"µ.
The aim is to exclude unused pictures or snippets, and to optimize the CHM size.
After the first test, I can see that some topics linked to the Alias file are excluded from the target.
I'm surprised about that because the Alias file is linked to the target, so if the topic is in the Alias file, it is linked "indirectly" to the target.
is it a bug ? or have I misunderstood how the option works?

Thanks in advance
Béatrice