WAB Print Widget Error with Image Service

[Blihack]

I have a Web AppBuilder application on ArcGIS Enterprise 11.5 that includes a print widget.

After upgrading from 10.9.1, we recreated the custom print service through ArcGIS Pro. 

When certain image service layers are visible in the map, the print widget throws the following error and refuses to print:

 

The widget shows "Error, try again" and hovering over the red exclamation mark shows "Q.renderer.hasVisualVariables" is not a function. WAB seems to be struggling to output the legend, but the "Include in Legend" option is unchecked for this layer.

Troubleshooting I have tried:

1. I added the same web map to an experience builder app, added a print widget, and it was able to print the image service layer and legend without issues.

2. Unchecking the "Include Legend" option in WAB print successfully, but obviously we need the legend.

3. Confirmed that the image service has the same capabilities, parameters, and symbology as other image service layers that print successfully.

Is this a bug with WAB and the ArcGIS pro print service legends? Or is there some option that needs to be configured in legend?

Any help would be greatly appreciated. We have a dozen WAB apps and we are not able to migrate them all to experience builder immediately.

[Blihack]

We were able to fix this issue by reuploading the orthophoto layer to our portal/image server and adding it to the web map again. However, changing the symbology of the ortho layer caused the issue to reappear. Even changing the symbology back to the default did not remove the issue, it had to be readded to the web map again.