These type of failures seem to be happening a lot with newer Thunder 380 & 380CC pistols. It makes me wonder if Bersa ramped up production and cut quality control after Sandy Hook since we have the same problems with both if our 2013 Thunder 380s.
These Failure To Feed and slide not locking back on the last shot are caused by the slide not traveling back all the way.
That is either caused by you or the gun. If your thumb is rubbing on the slide, it may slow to where it fails to cycle properly. Then there is the dreaded and misunderstood limp wristing. If your hand travels back it due to recoil it may take some of the energy away that is needed for the slide to complete its travel back. Keep a firm crush grip and lean your body into the pistol.
Now if it is the guns fault, that could be caused by not enough lube, too strong of a spring, poorly machined or finished parts. To fix try using a Teflon based grease instead of RemOli or CLP which runs all over and does not stay on the rails where you need it. Make sure that the spring is put back on the right direction with the muzzle end at the 12 o clock position. Take an hour with your unloaded Bersa and work the slide several hundred times while watching TV. Since it is a new gun, any imperfections from the factory may loosen up after shooting 200+ rounds through it.
I have noted that these problems are not present when shooting self defense JHP or +P ammo such as Buffalo Bore.