Why would the same FB insights query work in a browser and Graph API Explorer, but return null with PHP SDK? - facebook-graph-api

Question

As you can see in this picture
I have a valid long-life Access Token for my app (390068587730802) with the following permissions: ads_management, manage_pages, read_insights, user_friends
I can use it to get data on another accessible app (50813163906) using the Graph API Explorer,
$facebook->getUser(); does return my user id
HOWEVER, I get NULL from the same request via the PHP SDK.
I have tested locally on xampp and on an apache server. I have updated the PHP SDK today to include the latest changes surrounding offline_access and long life tokens. I have read dozens of posts and FB documentation. I´m glad to read more you think will help, but please note that my token is valid, long lived, and I am successfully getting "/me" from the graph API. All of this happens under http or https.
UPDATE "Facebook: Sorry, something went wrong. We're working on getting this fixed as soon as we can."
As seen in this next picture below, I´ve var_dump´d the CURL options to verify the correct access_token and URL is actually being called. Furthermore, I can copy these urls directly into the browser and get complete data return!!
If during my testing I have created "two active sessions" - as some docs warn - how can you test for that? Most importantly, why would the same FB insights query work in the Graph API Explorer, but return null with PHP SDK?

Answer 1

It turns out that "since=30 days ago" was giving a 400 (bad request) response. This error was not showing up in the CURL errors. Only via
curl_getinfo($this -> ch,CURLINFO_HTTP_CODE);
When i changed
$period = "{$period} days ago";
to
$period = urlencode("{$period} days ago");
//or
$period = strtotime("- {$period} days");
everything worked via CURL.