A sketch1 suddenly dubbed sketch1->?

Hi,

I am working with this part and suddenly, the boss-revolve disapears, the sketch1 is now dubbed sketch1->?.

So, I deleted the boss-revolve, and re-created another one, with the sketch, unchanged.

But what means this adding of ->?, why the boss-revolve suddenly disppeared ?

The story don't end here : I want to make a sweep-cut, with sketch2 as profile, the Helix as path : I can't get the sweep option, in the list of cut features.

Do you see the problem, here, too ?

Tx for your help.

SolidworksSketching