Layers are not imported from sketch

Principle Version: Version 5.10 (5021)
macOS Version: Mojave 10.14.6
Sketch Version: 65.1

Description of what you need help with:
When I try to import a sketch page into Principle only a rasterized single-layer version of each artboard are imported. In other words, no sub-layers are available for animation.

Steps to reproduce the behaviour:

  1. Click ‘import’ button in the Principle header
  2. Choose open sketch file from dialog
  3. Click ‘import page’ button

Screenshots/Sketch File/Principle file: (if applicable)