Hey @dan,
There seems to be a bug in 1.8.0. I think I ran into it a long time ago, but forgot about it until now. It seems that any layout created from a template cannot access the Library to add media to the newly-created layout.
EXPECTED BEHAVIOR: Clicking Library will display the media library picker.
ACTUAL BEHAVIOR: Clicking Library closes the region timeline modal and a 404 error in encountered in the inspector.
STEPS TO REPRODUCE
- Create a layout.
- Save as template.
- Create another layout, using our newly-created template.
- Edit the timeline for a region, click Library
Please let me know if you require additional documentation.