The -0 SSID could be coming from the "official AX.25" repository but the problem code isn't in the released source tarballs. You might try reverting to the older published version of code or maybe use VE7FET's version of the AX.25 code which has a lot of fixes, etc. that the "official" AX.25 repo still doesn't have:
http://code.google.com/p/linuxax25/
ARM binaries *are* available. This alternative code repository was originally maintained by F6BVP of FBB BBS fame as he had issues with some of the accepted patches (like this -0 SSID issue).
--David KI6ZHD
Another issue I'm having (AX25/netrom) is that we have to type a fake "-0" when connecting to a callsign with no ssid...why is this behavior the default? Any way to stop this and revert to just the callsign with no ssid? Users have no way of knowing that they have to add a -0, and so cannot connect to any station unless it specifies an ssid..thus, thinking the station is not available, we lose the user...there's not a TNC that I know of that does this, but linux ax25(and netrom) sees fit that this should be the standard?