Hi, just following up on this in case it ever helps anyone, basically the system message banner had characters causing the IDP commit script to fail upon parsing the config.
The exact message is below, the ▒▒▒ characters were somehow put in place during an upgrade( I cant see a user actually putting these in!), replacing blank spaces in the config.
A second SRX has the exact same banner message but does not display the oddball characters.
*********************************** Warning ************************************ *▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒* * You are about to access a protected resource. Unauthorized Persons will be * * prosecuted to the fullest extent of the law. This will be your only warning. * *▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒* ********************************************************************************
Hope it help!