Was retested here and no problem can be seen.
Steps:
1. Drop TAdvGlowButton on form
2. Drop TImageList on form and add at least one bmp
3. Set AdvGlowButton.Images := ImageList1;
3. Set AdvGlowButton.Images := ImageList1;
4. Set AdvGlowButton.ImageIndex := 0
-> Imagelist image appears on AdvGlowButton.