RLE segmentation mask visible in dataset thumbnail, but invisible in annotation preview/editor

Hi Roboflow team,

I’m seeing an issue with displaying segmentation masks encoded as RLE.

Problem

In the dataset grid / thumbnail view, the annotation mask is displayed correctly on top of the image.

However, after opening the same image in the annotation preview/editor, the mask is no longer visible. The annotation still exists in the left panel, but it is not rendered on the image.

Expected behavior

The RLE segmentation mask should be visible both:

1. in the dataset thumbnail/grid view,
2. and after opening the image in the annotation/editor view.

Actual behavior

The mask is visible in the thumbnail, but invisible in the opened image view/editor.

Example

In the dataset grid, the purple vessel mask is visible correctly:

arcade__000268.jpg

But after opening the same image, the annotation is listed as vessel, while the mask overlay is not visible on the image.

Screenshots

I attached two screenshots:

1. Dataset grid view — mask visible correctly.
2. Annotation/editor view — same image, mask invisible.

Dataset / annotation details

• Task type: instance/semantic segmentation
• Annotation class: vessel
• Mask format: RLE
• Example file: arcade__000268.jpg
• Browser/app: Roboflow web UI

Additional note

This looks like a rendering/display issue rather than a data issue, because the same mask is rendered correctly in the thumbnail view.

Could you please check whether RLE masks are handled differently in the dataset grid renderer and the annotation/editor renderer?

Thanks!

Riproduci il problema con arcade__000268.jpg e la relativa annotazione vessel in RLE nella UI web di Roboflow. Confronta il renderer della griglia del dataset con la vista di annotazione/editor, quindi verifica che l’overlay della maschera sia visibile in entrambe le viste mentre l’annotazione rimane elencata nel pannello sinistro.