Last tested with LibreOffice V 220.127.116.11
Created a Draw document with the default layers and inserted a single shape in each layer. Made sure all layers were set to Visible and to Printable as well.
Exported as Pdf with
- nothing checked under 'General
- Tagged checked
- Tagged and Hybrid checked
Resulting Pdf(s) opened with
Foxit Reader V 18.104.22.16897
Adobe Acrobat Reader V 2019.0.10.20098
No multiple layers found. Everything merged into a single layer.
Steps to reproduce: Do as I did.
(The Hyprid opened with Draw contained the layers.)