Just a point here, you seem to know what you are doing but just to make sure, you reveal the SSID by capturing a probe request/response. To capture this, you need to have a client associate to the network and essentially capture a 4-way handshake.
Here is what I would do:
Code:
airmon-ng start wlan0 -w capture
airodump-ng -c 5 --bssid 00:25:00:FF:94:73 mon0
aireplay-ng -0 5 -a 00:25:00:FF:94:73 mon0
aircrack-ng capture.cap
If running aircrack didn't show the SSID, I would open the cap file in wireshark and look for the packets just before or in the 4-way handshake (more specifically at the info tab) and look for "SSID=XXXXXXX".
*APs that don't broadcast their SSID still send out beacons, else the clients wouldn't know theres anything there in the first place. They just don't give out the SSID*
Also, make sure your card is not connected to an AP in wlan0 and that you only have it in one instance of monitor mode so it does not get confused.
HOWEVER, at the end of your post you said it has a power of -1. I have had the same exact thing happen to me, and I get very similar output when I try to find the the ssid is... ex: <length: 0> and Pwr -1.
I think this may just be a probe or beacon of some sort from a client floating around but I haven't been able to figure that out.
Good luck though!