How do I export layers that are cropped to the document in Affinity Photo?

Quick Explanation

When I try to export slices created from layers, the output files are not cropped to the document. I can "Rasterize & Trim" each layer to get the desired output, but I’d like a non-destructive way to do it. Any ideas?

Detailed Explanation

I’m taking photos of a number of products, each of which have 6 photos of the same size.

My goal is to keep one AFPhoto file per product with each of the 6 photos as layers, with all edits made non-destructively, and then export each photo with a lower resolution (for web) in bulk to a designated "Processed Photos" folder.

Here’s my current, problematic workflow:

1. Open up all product photos as layers in one AFPhoto file
2. Perform various edits, including rotating, cropping, etc to each
   layer
3. Create slices from layers in Export Persona
4. Set up export settings and export each slice to the destination
   folder

The problem is that the output files are not cropped to the document boundary as shown in AFPhoto.

I can solve this problem by selecting each layer and choosing "Rasterize & Trim", but this is destructive, which I don’t want.

Appreciate the help. I’m guessing it’s a pretty simple solution, but I’m an amateur at this software.