Good morning CryGen,
I am glad you were able to figure it out. A few things I would like to point out to possibly help for the future (and for others that might want to import as well).
HeroEngine, unlike other engines, use each area (chunk, level, zone) with its area offset (absolute 0 position) instead of full game area. This means you can build a world as small or large as you like. So do be careful with your offset for your heightmaps.
Often times it is easier to break them up into the size you want for each area, import then link up. This way you will not have any issues with offset issues (such as arrival points, pathing, triggers, etc). It also allows for a much smoother transition between areas.
For imports being flat, (this is often a question i had seen in the past), finding the scale for import can be tricky and really depends on the resolution and the programme you used to build the heightmap file. So finding that perfect scale is different for everyone. I generally suggest testing on a small map or a piece of it to find the scale and note that for all future imports.
If you have any additional questions please feel free to ask. We can help with a combination of our experience as developers and team members as well as links an any relevant references.
On a side note, please do post up what you figured out so it can help other developers that might have the same questions or difficulties. It can also help us figure out future updates and what we might want to adjust or add in to make things easier as well in the engine.
