When exporting images with additive blending in Spine, the result can appear black if the background is transparent. This is because additive blending relies on the background color to produce the desired effect, and with a transparent background, the blending doesn't work as expected. To resolve this, you can either avoid using additive blending for static image exports or ensure that your images use transparency instead of black. Additionally, when exporting, make sure that your Spine version is up-to-date, as older versions had issues with additive blending during export.