Don't know if this is what happened to you but I've had a couple of incidents recently where the tail of the cone was only just outside the exclusion zone circle and, while scooping for an FSD boost, I've been buffeted around into the zone and dropped out. Is it just me or is there pretty much nothing you can do to save yourself when this happens? The buffeting means you can never stay lined up with either a target system for a high wake nor the escape vector for a low wake long enough to actually jump out.
you can escape, but it all comes down to what outfitting you have, if you have a decent distributor and dirty drives / clean drives with some decent agility - hitting boost consecutively while the front of the ships is vaguely pointed towards the escape vector / target system and your out (have the FSD fully charged with "align to vector" then the countdown starts and buffeting stops once you boost the ship in a straight line) FA off can also help here too but thats a whole other skill set
i predominantly fly small ships, and the DBx and Dolphin achieve this fine even with 4D thrusts (g5 dd and typically 3D dist with eng focused for minimum two boosts), and i've dropped in many neutrons and escaped, i've experimented the same with a Conda and thats a pig to get out in an exploration build / nigh on impossible, but stick some decent thrusters on it and a huge PD capable of boosting and it too can escape - but then you lose the jump range advantage of the conda
if you are running a conda with 4D thrusters and a 1D distributor then its game over unless your lucky
@op in the plume.
as Alec says some exclusion zones are extremely close to the plumes and you could have been pushed into the exclusion zone, if the plume did drop you from SC then it would be like the disconnect bug when neutrons first came in - you can escape these simply by going back into SC (low wake) not high wake as there is no escape vector or "align to vector" required. - any ship can do this without too much lasting damage.
the only other way to drop into the plume is if your FSD is below 70% (i think its 70% IIRC) a small chance but its there at anything less than 70 (and the chance increases as you get lower) to drop you from SC at anytime, if your scooping a neutron to boost your fsd it could drop you in the plume at the same time.
in the above scenario - video below;
[video=youtube;sXE9W2pb8IE]https://www.youtube.com/watch?v=sXE9W2pb8IE[/video]
thats my experience with NS anyway, i did alot of beta testing in the previous betas with broken FSD's escaping neutrons etc (what better place to try with free credits

) but the thread is long buried so i cant find it, i also have a video of escaping using escape vector ill try and dig it out and upload.
edit ** found one reference to it;
https://forums.frontier.co.uk/showthread.php/375648-FSD-Malfunction-Neutron-Jumping-Question/page2
^^ this thread also reminds me i never checked to see if the "bug" was still in LIVE lol, i may use my PC account to go find out.