Github's "source code (zip)" is incomplete? (folder missing)

Question

On Github repository I have one file ("changelog.txt") and one folder ("source") containing, as the name suggests, the source code of the zipped executable (the program). See Github Repository.

However, when I go to the release page - see Github Release - I can download the zipped executable, but when I try to download the source code - see Source Code (zip) - there is only "changelog.txt", and the entire "source" folder (containing the actual code) is missing.

I understand that Github's "Source Code (zip)" is auto-generated based on the content of the repository, so I deleted the old release, and created a new one + re-uploaded the zipped executable, but it doesn't seem to work and I still have only "changelog.txt" when I try to download the source.

It's not the end of the world since the source code is still accessible from the repository (see the first link), but such a problem could potentially annoy the people who would like to download the source from the release page.

Is there a solution ? Or did I do something the wrong way ?

Thanks for your answers, and sorry for my bad English (it is not my native tongue).