Differences between sandbox and none in the isolation mode of plugin

Hi Guys,

I have recently come across a strange problem. I have a global action called through JS to trigger a plugin step, in this plugin, I will post a web request using sync method and return a output parameter to action (IPluginExecutionContext.OutputParameters).

At the first, I used none mode in the plugin, it can send this post request successfully and implement IPluginExecutionContext.OutputParameters to return to action, however I found that my JS code received a null result return value from action. After that, I changed to sandbox, JS can receive correct return value!!! The same code, it's just that the plug-in mode(none or sandbox) is different.

Anybody know why that is, is this a bug in CRM? BTW, I'm using dynamics crm on-premise v9.0.

Look forward to your answers~

Thanks,

Stone