To verify that I cannot hit anything before I encounter enemies, I take the melee weapon in my hands and go into the crouching position. When I now right click on my mouse and want to go in the attacking position, my character flickers up and down until I no longer right click. That additional bug shows me, that I will not be able to hit something with my melee weapon.
This bug occured also with other players I know. Interesting is also, that when the bug occures, for other players I still hold my main fire arm, although I am holding my melee weapon on my PC.