Are you seeing a list of every version of your ScopeNox skin in the repo listing? If so I don't think you're doing versioning the way Kodi is expecting it. It might be helpful to see your addons.xml file from the repo as well as the addon.xml file from the actual repo and the directory structure of the repo. Here's the addon.xml for my actual repo for instance:
xml:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<addon id="repository.skins.pkscout" name="pkscout's Skin Modifications" version="1.1.1" provider-name="pkscout">
<requires>
<import addon="xbmc.addon" version="13.0.0"/>
</requires>
<extension point="xbmc.addon.repository" name="Skin modifications by pkscout">
<info compressed="true">https://raw.github.com/pkscout/repository.skins.pkscout/helix/addons.xml</info>
<checksum>https://raw.github.com/pkscout/repository.skins.pkscout/helix/addons.xml.md5</checksum>
<datadir zip="true">https://raw.github.com/pkscout/repository.skins.pkscout/helix/download</datadir>
<hashes>false</hashes>
</extension>
<extension point="xbmc.addon.metadata">
<summary lang="en">Install skin modifications by pkscout</summary>
<description lang="en">Download and install skin modifications from pkscout.</description>
<disclaimer lang="en">These skin mods are only lightly supported.</disclaimer>
<platform>all</platform>
<nofanart>true</nofanart>
</extension>
</addon>
and the xml for the addons.xml file:
xml:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<addons>
<addon id="skin.estuary.leia.pkscout.mod" version="1.1.14" name="Estuary Leia Mod (pkscout)" provider-name="pkscout, phil65, Ichabod Fletchman">
<requires>
<import addon="xbmc.gui" version="5.14.0"/>
</requires>
<extension point="xbmc.gui.skin" debugging="false">
<res width="1920" height="1440" aspect="4:3" default="false" folder="xml" />
<res width="1920" height="1280" aspect="3:2" default="false" folder="xml" />
<res width="1920" height="1200" aspect="16:10" default="false" folder="xml" />
<res width="2040" height="1080" aspect="17:9" default="false" folder="xml" />
<res width="1920" height="1080" aspect="16:9" default="true" folder="xml" />
<res width="2560" height="1080" aspect="21:9" default="false" folder="xml" />
<res width="2338" height="1080" aspect="19.5:9" default="false" folder="xml" />
<res width="2160" height="1080" aspect="18:9" default="false" folder="xml" />
</extension>
<extension point="xbmc.addon.metadata">
<news>
v.1.1.14
- better support for 4 digit channel numbers in PVR dialog seek window
- fixes from Estuary 2.0.16 in Kodi 18RC3
</news>
<summary lang="en_GB">pkscout's mod to the Estuary skin by phil65.</summary>
<description lang="en_GB">Various mods to Estuary, including Artist Slideshow support and ability to customize home screen and home screen widgets.</description>
<disclaimer lang="en_GB">This mod is only lightly supported.</disclaimer>
<platform>all</platform>
<license>CC BY-SA 4.0, GNU GENERAL PUBLIC LICENSE Version 2.0</license>
<forum></forum>
<source></source>
<assets>
<icon>resources/icon.png</icon>
<fanart>resources/icon.jpg</fanart>
<screenshot>resources/screenshot-20170506-01.jpg</screenshot>
<screenshot>resources/screenshot-20170506-02.jpg</screenshot>
<screenshot>resources/screenshot-20170506-03.jpg</screenshot>
<screenshot>resources/screenshot-20170506-04.jpg</screenshot>
<screenshot>resources/screenshot-20170506-05.jpg</screenshot>
</assets>
</extension>
</addon>
</addons>
When I update the skin I bump the version number in addons.xml, update the news section, create a new MD5 hash, and then upload a zip with the correct naming convention (which is skinid-versionsnumber.zip). With that when I go to a Kodi instance with the repo installed and force an update, the skin update downloads with no problem. And if you have auto update enabled for addons, then Kodi will check periodically and update as needed.