when I saved the project and exported the video, some of the keyframes were still EMPTY, and yes, I even drew by hand, but I didn't upload any photos, so what's the problem?

Bug Reports
1

when I saved the project and exported the video, some of the keyframes were still EMPTY, and yes, I even drew by hand, but I didn’t upload any photos, so what’s the problem?

2

There isn’t any obvious reason why this would be happening, so you’re going to need to provide some more information about your issue. Are the keyframes empty when you preview them in Pencil2D or only when you export? What format are you exporting to? What operating system and what version of Pencil2D are you using?