I figure it out!!
I spent a few days on this. I'm using the current versions of Blender and RCP as of April, 3rd, 2025. At first this did not work, but I repeated my steps and tried again, and then it start working. I think there are some memory issues in RCP when previewing the scene (especially if loading assets with the same name and replacing what's there). I replicated the workflow with all new files and names, and it went smoothly.
Note: Use the Star icon in the NLA strip editor in Blender, or have the action you want to export active/selected/in the stash. This is the one that will be exported.
Export your model as a USDC from Blender. Uncheck animation, include textures/materials. This will be your visible model object.
In Blender, Star the NLA strip you want to export. Select the model. Export as a USDC, Selected Only, check Animation, uncheck everything else (materials, textures). However, you MUST include the Mesh.
Repeat step 2 for each animation.
Note: you will see your object as a pink striped object in the RCP Project Browser, and the correct animation should be visibly playing in the preview window on the right when selected.
Notice: Keep the following steps on the model parent object in the RCP scene tree.
Add the Animation Library Component to the model parent.
Click the + to add an animation.
Choose the "animation" USDC's you exported from Blender.
This will provide access to the multiple animations on the single model object.
To see these animations in RCP Preview, you'll need to create a timeline. To do that, follow these steps:
Create a new Timeline
Set the play head where you'd like
Select your parent model object in the scene tree
In the Animation Library Right-Click on the animation you want to play and choose Insert into Timeline.
Note: you can manually drag an Animation Action from the Timeline Actions panel if you'd like and set it up that way, but this is quicker.
Next, you'll need to play your Timeline in RCP. The easiest way to do that is:
Add a Behavior Component to the model.
Add an OnAddedToScene behavior
Choose your Timeline as the action.
When you preview the RCP scene in RCP, you should now see your animation playing on your model object.
These animations should also be accessible with Xcode by using the names they have been given in the Animation Library. I believe you can also edit those names there as needed.