Before I start, I found this post a few years back with the same problem, but doesn't have any solutions.
My coworker and I both -- 2 different user profiles, 2 different computers, 1 ST8, 1 ST9 -- can't get the Project o Sketch options to allow associativity.
All of the Inter-Part links options are checked in the Solid Edge Options.
The part that we have an issue with is a mix of Synchronous and Ordered features. The sketch we are trying to project an associative edge to is within an Ordered feature.
I'm at a loss to figure out why the option is greyed out.
I have run into the same thing. Never figured out exactly why. Sometimes I had to re-make the part, other times I did get past it but don't remember how. I think it had to so with the sequence of events in ordered. IE one of the part's that the sketch is realted to moved to later in the sequence.
The part is being edited in-context, accessed through the Right-Click -> Edit menu.
I have also had this problem intermittently, over many years. Never really found the reason, but at one stage I was thinking it was something to do with if 'Project to Sketch' had previously been used in the part and, if it had, redoing the previous projections and then the Associative button would be selectable.
I would love to have a definate solution to this.
@SeanCresswell The only subassembly in this file is the part that the tool is designed around. All interpart links are between the tool's components, so they all exist at the top level.