Hybrid development models

Are there any other BAs or PMs that work in a hybrid (waterfall/agile) delivery model?

I used to think hybrid was pretty straight forward based on a lot of places I've worked that don't do agile well. But i have found myself in a truly hybrid environment in my current role and it is very challenging. It seems this is agile ish with Waterfall reporting if I had to try and label it because the higher ups expect a full LOE at the beginning. Not only that but we're doing user stories and requirements.

What kind of models have you worked in? What was the most challenging thing about it and how did you overcome it?