Using the SDK 2.0.0 on MacOS
I made the attached GIF in Photoshop (using File->Export->Save for Web). It plays fine in QuickLook and every GIF-viewing tool I have easy access to.
I import it into the project using graphics.imagetable.new(gifFilename), and it seems to draw a blank frame for frame 3.
In the pdx bundle, the pdt file that gets generated has a nearly-blank frame 3. It seems to contain only the delta against frame 1.
I know there's something off in our animated gif decoding, one of the card animations Christina made for Forrest Byrnes had weird artifacts that I couldn't sort out. This gif is weird. It has full images for frames 1, 4, 5, and 6, a sub-image delta for frame 2, and a full-image delta for 3. Its frame disposal methods don't really make sense--it looks like it's saying to composite frame 2 over frame 1 (makes sense) but to replace the image for the rest of the frames (doesn't make sense for frame 3). I'll see if I can find some gif rendering code online to see how it deals with this.
In the mean time I think your best bet is to turn off optimizations in your authoring tool, if possible, so that pdc doesn't get confused. Otherwise you can use Optimize animated GIF with the Coalesce (unoptimize) option to replace the delta/partial frames with full size frames.
LOL I didn't even remember that. I guess the lesson is don't use Photoshop to make GIFs (which may be a good thing since it was one of the last reasons I'm still paying for Photoshop).
Hello from 2025! I finally sat down and figured out the tricky details of animated gif disposal modes and pushed a fix for this. Not sure if it'll be in 2.7.0 or not, but just noting it here for the record.