Why no image of what is printed?  

RE: Why no image of what is printed?

Initially it sounds like a QOI vs PNG issue. Here's the section from the firmware release notes that introduced QOI.

QOI instead of PNG (XL, MK4, MINI)

Until this release, the thumbnails for G-code were in PNG format, which was rather resource-heavy. We have decided to switch to another format called QOI, which is way less demanding, and we can utilize the freed-up resources to bring more features in future releases.

The only downside of removing the support for PNG is that all the G-codes sliced until now, won't have a visible thumbnail on firmware 5.1.0 or newer. For now, the only solution is to reslice the G-code in PrusaSlicer 2.7.0 or newer.

In expert mode you can look under the printer settings and see what file formats are listed for G-code thumbnails.

RE: Why no image of what is printed?

So how do I change it? PrusaSlicer 2.7.4  This is what is set for the G Code Thumbnail and it is locked: 16x16/PNG, 313x173/PNG, 440x240/PNG.

RE: Why no image of what is printed?

Not 100% sure but you do have binary gcode enabled, right? It should be a few lines down below the thumbnail options. 

Beyond that maybe check if there are any configuration updates or I guess you could try entering,

16x16/QOI, 313x173/QOI, 440x240/QOI, 480x240/QOI, 640x480/PNG

in the box and saving it as a new printer configuration.

RE: Why no image of what is printed?

Thanks, I will give it a try. That option is under Configuration/Preferences/Other.