PJSIP has dissappeared from Freepbx 13

I was trying to get an extension of 36609 to register and every time I did all the PJSIP clients went offline for a few minutes. Then everything to do with PJSIP disappeared from the system and previously working phones will not register. PJSIP has gone from the extensions tab.

I’m not sure if this extension number is a code to call a function but whilst PJSIP was working I could add other extensions and register without issue.

Any advise would be appreciated.