I know the thumbnail images have been buggy lately, but I've tinkered with it here and there trying to figure out what's making the system not generate a thumbnail when you upload a comic page. It's been happening only to certain people for a long time, and I've tried collecting data, and still no answers have emerged. I'll keep an eye on the situation, though. Plus, I've had other obligations to attend to, but hopefully I'll find a lead sooner or later... Thanks for hanging in there!
