I have had the exact same issue during hard mode.  also during normal mode there have been times where i have collected the souls and not had them in my inventory after match.

Just had this happen to me on the incursion.

Yesterday it happen to me at C4 trial map, spot in upper cave, gold was hanging from ceiling, you could E click on it, got a message, that gold ingot was collected, but it never fell from ceiling.

Here is a video showing this bug in action..

When you click E on the gold thingo the Bars are not being dropped to the ground for the player to pick up.

Yup! Same thing for me, too. Multiple times. Ch4 is where I played last and had it happen. Same spot, too: in the lower caves between the 2 middle lanes.

Well after i just got 7 souls after i finished the map a golden ingot spawned BUT i coudent pick it up nothing happened it said: A golden ingot has spawned but i coudent pick it up i tought it buged and it was invizible so i tried crafting the key and it didnt work so i coudent open the chest. PLEASE FIX.

I did a solo incursion and the gold did not spawn for me to be able to make the key, so I was unable to collect the chest.