Em.. as all my experience is in Web, this is a new one on me.
I've built a metadata plugin that adds an 'enum' drop down menu and a 'string' field.
Works fine as a .lrdevplugin but when I change the extension to .lrplugin it gives an error (yes I've removed the dev version and then added the .lrplugin via the plugin manager).
When I Add, I get the following error:
**** Error 1
An error occurred while attempting to load this plug-in.
The following error occurred while running Info.lua: PluginInfoProvider.lua:2: attempt to call global 'require' (a nil value)
Hmm... reloading made it work this time, but not others.... very odd..
Not directly related to your problem, but you don't actually need to remove the .lrdevplugin version of the plugin when you want to test the release version.
If you have both .lrplugin and .lrdevplugin versions installed at the same time LR knows they are the same because of the shared LrToolkitIdentifier value. LR will only allow one to be enabled at a time. So when you want to change the version you are testing simply enable one version of the plugin and the other will automatically be disabled. This is really handy when people are asking for help for the released version of your plugin, and you are working on a new version of the same plugin.