I just tried the new appImage for Ubuntu

./Void-1.2.0.25104.glibc2.29-x86_64.AppImage

When I run it, I get the following output:

sed: /tmp/.mount_Void-1nTqzUt/lib/x86_64-linux-gnu/libselinux.so.1: no version information available (required by sed)
/tmp/.mount_Void-1nTqzUt/AppRun: 10: exec: /usr/share/void/void: not found

The warning from sed is not a blocker, but the second line is — the app doesn't start.

Investigation

Let's go:
I extracted the AppImage using:
./Void-1.2.0.25104.glibc2.29-x86_64.AppImage --appimage-extract

Then checked the contents:

cd squashfs-root
find . -type f -iname 'void'

./usr/share/bash-completion/completions/void
./usr/share/void/bin/void
./usr/share/void/resources/completions/bash/void
./usr/share/void/void

the binary exist inside the extracted AppImage

./usr/share/void/void

And if I run it manually:

chmod +x ./usr/share/void/void
./usr/share/void/void

…it works as expected.

Conclusion
It looks like the AppRun script is trying to launch the binary using an absolute path:
exec /usr/share/void/void

Please consider changing the AppRun script to use a relative path instead, like:

exec ./usr/share/void/void "$@"
ok
exec "$(dirname "$0")/usr/share/void/void" "$@"

Dylan