So to clarify a bit more.
Enemy A was leaving a window and had gone up to the roof. In the understanding they were standing on the roof, the player used it for contiguously travelling through the floor, up the wall and to what was then considered the floor where Enemy A was now standing. If LOS was lost, probably a concealment status from Player A (50% miss chance) might have been a good route?
Secondly, thank you all for your thought out answers and input. I will bring this to the DM for at least a little more clarity from others experiences and perspectives.