Creo is incredibly modal - and often it won't let go of a mode it's stuck in. This gets me all the time - maddening. I use Ctrl-A to reactivate the window and often that bumps it out of it's stupor.
I don't know of any connection between the cross hatching in assembly or part modes that updates properly back to drawings. (I might not know that yet.)
I'm not sure of the differences between 8 and 9. I'm in 9, so it might be a little different? With cross hatching, it will select in some modes (while in Layout, Tools, and some others), but won't allow you to select it in other modes (Annotate, Table, Sketch). Also, check the filters (bottom right). If it is stuck in one of those modes, even though you have actually clicked Layout for instance, sometimes it just won't. For me, I've had marginal success just trying to select it in different modes.
I also had a bunch of trouble with some legacy models. They've changed something along the way and it does not handle the older parts correctly all the time. (Mostly, but not always.) Tech supports says it's my imagination, even after they watch it in a Teams session. The inherited model might be something that Creo is not handling properly. I don't know, but I wouldn't rule it out. Good luck.
