it appears to be random.
I started the game earlier and had a bandage in my hands :)
earlier still i had a gas lamp with no canister (even tho it wat attached to a canister in my inventory)

I'm also guessing that you would be able to put the fryingpan/stove into a protector case giving you 11 items in a 6 slot box

(I shall test this later)

So you were in a public server.
losing gear and characters is common in public servers. the devs have more important things to do than trawl through user files replacing lost items (that would be literally all they had time to do if they did)

"we are really sorry but we are not going to play DayZ again because it is not the first time this happened to us"

if losing gear and 10 hours of play bothers you that much in an Alpha game you agree to play every time bugs and all then you should follow your own advice tbh

Come back to the game later when it is more stable.

Calm down, you didn't lose your stuff. try going back to the original server you were on and i will bet it is all back.
(also remember that every time you play you click "I understand" when it tells you there WILL be bugs and you can lose gear and characters)

Anyways
its all down to server settings.
some will be private some will be public, some will have persistence on or off (not working atm)
this affects how the character is spawned.

say you loot up on a server on a private hive. then go onto any other server that is private all your gear will be there.

if you then go to a public server you will get a new character (if you loot up that character then that gear will be available on any server with the same public settings). so essentially you have 2 stored characters.

a bit of a workaround to get the gun back without logging

if you can't pick up the gun once it drops at the fence (lets say its an SKS for clarity) . drop the gun you have on your back (mosin) close by, open your inventory and have the dropped SKS in the vicinity before you drop the mosin)

then pick up the SKS that dropped when you jumped the fence (it will go on your back) then pick up your mosin into hands. (you can then swap them back over by dragging and dropping gun on back to gun in hands.

(I know it sounds scary and theres a chance you may lose 2 guns :) but its worked so far for me about half a dozen times)

had this happen tonight.
I was double carrying.

SKS in hands mosin on back.
I jumped a fence and he dropped the sks.
I jumped back over and the gun was on the ground but i couldn't take it into my hands.

I had to put the mosin on the ground, pick up the sks into main inventory (on back) then take the mosin into my hands. (then i could swap them over )

the whole idea of items leaving empty inventory slots when in your hands is crazy. it has opened up a huge can of worms

the inventory is far too fiddly as it is without adding even more micro management.

say you have a pistol in your backpack and put it in hand while looting (for safety)

and you pick up a can of something, it sometimes goes into 1 of the slots the pistol was using.(even if you have other empty single slots)

if you have no free 4 slot box you cannot put your pistol away.

nearly got killed by a zombie when this happened to me and i couldn't change to my axe with hotkey by the time i realized why i couldn't put the pistol away i had been hit a good few times.

another is if you chop a tree down that makes long sticks the stick will auto equip on the slot the axe came from on your back. (happened to me last night and i lost the axe too)