Found I can reproduce this for my Player Character:
@ western most of the two supermarkets in the western Cherno-Balota High Rise Buildings.
Approach the supermarket from the back, use the vault/hop key/function to mount the plinth at the back of the supermarket. Instead of climbing it, the player is placed in the (world) ground level. Loot/Items can still be gathered in this condition, and weapons can be successfully fired at zombies.