Thanks. I don't think Bummer dying has anything to do with Maples not giving me the task. I tried several things, e.g., talking to Maples before Viktor arrives, after, before talking to Viktor, after, etc. I was finally able to advance when I used the spawn menu at the Radar spawn point from Army Warehouses, waiting for Viktor to arrive, but not talking to him. Hopefully, that helps someone else if they run into the same issue.
Also, I gave up on using the ladder. Again, I tried several things; crouching, low-crouching, side-jumping, side-walking. I even went to the top of the ladder and jumped to various ledges. In the end, I just used the spawn menu each time.