This originally worked, then stopped and fixed (as reported in an earlier question https://wisej.com/support/question/uploadfiles-example-doesnt-show-pictures-on-flowlayoutpanel) and once more it oscillated to the non-working position. The picture boxes that were supposed to show up in the flowlayoutpanel do not show up.
It’s probably because you are using the experimental build I sent you to test the performance issues. It works with the build I have which solved the issue with your test app when adding invisible controls. However, there is a different issue related to the fix for the animated gif, the encoding is now wrong and uploaded pngs show as a black box using the sample because System.Drawing changes the RawFormat to MemoryBitmap. Fixed as well in our development build.