Some plugin authors have been having some issues uploading plugins when using older versions of the plugin-publish plugin to publish their plugins. This is due to some bugs in the older versions of this plugin coupled with some S3-related infrastructure changes made in the portal. These bugs were fixed in 0.9.7 of the plugin-publish plugin, which was released in December 2016.
All plugin authors need to upgrade to the latest version. Older versions result in a plugin version that appears in the portal but has no artifacts. We are working on some improvements to detect this state and stop new plugin versions from being activated when it occurs, but the only fix is using a non-broken publishing plugin.
In the meantime, if you have published a new version of your plugin and it is missing artifacts, let us know and we will delete the broken version to allow you to re-publish it. Please accept our apologies for the inconvenience.