Hi Clay,
This feature allows you to view your model during design as it will show in the experience based on the sequence selected. It is a check box found under the sequence selector for the model.
Hope this helps!
Hi @tmccombie,
This is great and I"m already finding this useful, but now I"m going one of those customers that asks for more. 
It would be great if the sequence could be applied when capturing the detection position for a model target. While it's great that it can be applied at design time, so when I'm building the experience, I can see what the model will look like when loaded based on the sequence, if I'm using a model target, I'm back to having the mess of everything visible for my detection position, so there's often extra stuff that will get captured in the outline.
To get around this, I've sometimes had to upload another model file that has the model "clean" and then use this model as the target and make it not visible in the experience.
Many thanks,
Allan
Perfect timing on this release, i was minutes away from redoing hours worth of work.
8.3.4 provides a fix for the mode item problem I was having. Prior to 8.3.3 you could get a modelitem to "refresh" it's coordinates, as in set them back to what they are in the assembly by typing a "/" after the occurrence ID. This was not working in 8.3.3. but it is now working again in 8.3.4.
Here is the procedure. Simply select your modelItem and add a slash "/" at the end of the occurrence ID. As soon as you type this you should see the coordinates update. You can then delete the slash and the coordinates will remain. I'm not sure what will happen if you leave the slash on the end.
Before anyone mentions that I could have just typed in 0 for "z", this was a bad example. Most of my items have non-zero values for the correct coordinates.
As best i can tell there is now a checkbox under "Sequence" for Model widget items that says "Apply sequence at design time" If you check this the component visibility defined in the sequence is applied in the design 3D view, but not any animation steps in the sequence.
All my sequences start with the parts in the same position so i'm not sure if you had Step 0 defined with parts in a different position maybe the parts in design would go to that location when you picked that sequence?
Yes, I was actually wondering if this feature might solve the problem I described in https://community.ptc.com/t5/Studio/Position-of-modelItem-is-wonky/m-p/565101
As for modelItem grouping, yes, it would be very helpful to have a BOM-like tree control to choose from. However, I've been able to get pretty far by hacking the "Component Occurrence" property. It's a hierarchical path to the part in the assembly, so to get ancestor sub-assembly for a specific part, just start deleting path components from the end of the path, and it will select higher "groups" or assemblies. For example, if your modelItem selects a part with Component Occurrence "/5/1/2", you can select the direct parent by removing the "/2" from the end, resulting in "/5/1". For a deeply nested, part, you can keep working your way up the tree until you get to the level you want.
You can also take a more direct route: in Creo Illustrate, select the subassembly you want to create a modelItem for, and open its Part Properties and check the Attributes panel. There should be an entry called "sBOM ID Path", which gives the string you need to reference this subassembly in within the assembly. You should be able to paste that into the modelItem Component Occurrence field and have it pick the right subassembly.
Also, a big THANK YOU to the dev team for getting Hololens support for newer versions of Creo Illustrate! 
@tmccombie Is the grouping of ModelItems under the parent Model new? This pretty big news on the large experience organization front!
