PowerPoint for Mac 16.111 incorrectly renders PNG images with transparency/shaded regions

Question

Environment

• Microsoft PowerPoint for Mac Version 16.111 (26061317)

Microsoft 365 subscription

macOS Tahoe 26.5.1

MacBook Pro (M3 Pro)

Problem

Several PNG figures that have displayed correctly for years are now rendered incorrectly in PowerPoint.

The figures are scientific plots generated outside PowerPoint and contain semi-transparent shaded regions (e.g., uncertainty bands). PowerPoint now displays large opaque red rectangles that obscure part of the figure.

The issue affects multiple independent PowerPoint presentations that previously displayed correctly.

Observations

The same image is rendered differently in different parts of PowerPoint:

The slide thumbnail pane displays one version.

  The main editing view displays a different, more severe corruption.

  
  Exporting the presentation to PDF produces the correct figure.

  
  The affected object is a PNG image, not a vector graphic.

  
  Saving the image from PowerPoint and reinserting it reproduces the problem.

  
  The issue appeared recently and affects multiple older presentations that were previously displayed correctly.
```**Request**

I am looking for a solution or workaround.

Specifically:

1. Is there a way to force PowerPoint to re-render or rebuild image caches?

1. Is there a way to reset PowerPoint graphics settings on macOS?

1. Is there a known workaround for PNG images containing transparency or alpha channels?

1. Can the graphics-rendering engine be changed or reset?

1. Is there a way to recover the correct display of existing figures without recreating them from the original source files?

The attached screenshots show that the PDF renderer displays the figure correctly, while PowerPoint itself does not.

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Answer 1

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Hi @Koko Armon

Based on the information you provided, I understand that you are experiencing a severe graphics-rendering issue in PowerPoint for Mac on macOS Tahoe, where previously stable PNG scientific figures containing semi-transparent alpha channels (like uncertainty bands) are suddenly displaying with large, opaque red rectangles. This artifact severely blocks the main editing view, though it appears differently in the thumbnail pane and completely disappears (rendering correctly) when exported to a PDF. Since this affects multiple independent, older presentations without any changes to the source files, it points to a localized regression in how PowerPoint processes alpha-transparency layer caching.

While I have attempted to reproduce this behavior within a standard production environment, the transparency layers are rendering normally on my end. To help isolate this behavior and provide you with the most effective workaround, could you please share a bit more context?

• When exactly did this behavior begin? Did it coincide precisely with an automatic update to your Office suite or a macOS update?
• Your current build, Version 16.111 (26061317), indicates that you are enrolled in the Microsoft 365 Beta Channel. If you happen to remember, what was the last stable version number where these figures displayed correctly?
• Test with alternative formats: If you convert one of the corrupted PNGs to a JPG (which flattens transparency) or embed it directly as a vector PDF image onto a blank slide, does the red block persist or does it render correctly?
• Sample Slide: To help me run deep-backend telemetry and replicate this exact asset failure, would it be possible for you to share a single, non-sensitive sample slide containing one of the affected PNGs via a private message?

Please let me know more details.

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