A new hint to know your decision ...
The USCIS phone call 800-375-5283 has different features for working hours (8am-8pm EST) and non-working hours.
In non-working hours (usually I do this after 8pm), the automated system is a male robot, and the case status is still in old fashion (with EAD clock and 150 days rule).
That male robot will read your status with EAD clock running or stopped, which enables you to know your decision accordingly.
And strangely my receipt number cannot be captured in the automated phone system (as if it disappears), so if anyone else with "Decision was mailed" status but cannot get your status through phone call system, please keep us updated.