Hello! Laurent. Thanks for the details.
It’s not a bug you can fix, it’s a long-standing limitation of placeholders in the Slide Master. The only reliable workaround is to use text boxes instead of placeholders, or to apply/automate autofit on the actual slides.
Your options
- Use text boxes instead of placeholders
Insert a normal text box on your Slide Master instead of a placeholder.
Enable Shrink text on overflow.
When you create new slides from that master, text inside that box will shrink correctly.
- Apply autofit on slides after creating them
Keep placeholders if you need the built-in structure.
Once you generate slides, select the placeholder, go to Format Shape → Text Options → Autofit, and apply Shrink text on overflow manually.
(This is tedious if you have many slides.)
- Automate with VBA
You can run a short macro to go through every shape in every slide and enable autofit automatically. This way, you keep placeholders but still get shrinking behavior.
See if this helps. If you need further assistance, just let me know.
Best regards,
Kimberly