Subaru legacy IV immubiliser problems

[KuMaPL]

Is there anyone here with a Subaru Legacy from 2005 experiencing issues with the immobilizer? My engine often refuses to start, and it's not a matter of the starter or spark plugs. Pressing the key fob button only works if I keep it in the ignition. Opening and closing the doors twice seems to help in those situations. It doesn't happen all the time, but it's quite frequent and becoming irritating. Can anyone share advice on completely disabling the immobilizer?