I already owned Armored Princess, and bought Crossroads. When I went to install Crossroads, I ran into issues with it not installing both products, and the other one vanishing from the My Games list. This prevented me from running the expansion.
I did come up with a workaround, that may help some other people. Here is what I did to cause the problem (maybe this affects everyone, not sure), and what I did to resolve it, incase people have the same issue:
Problem:
1. Have neither Armored Princess nor Crossroads installed
2. Start downloading and installing both at the same time
3. Crossroads finishes first since its smaller, and installs. Armored Princess download pauses, removes itself from the My Games list, and never installs itself.
4. Attempting to run Crossroads will say Armored Princess is not install and will not run. There is no longer an option to download Armored Princess.
Workaround:
1. Install Crossroads
2. Right click on Crossroads in My Games, and select Open Folder
3. Close Impulse
4. Rename the "King's Bounty - Armored Princess" to something else (do not delete it)
5. Launch Impulse
6. Now you can download Armored Princess. Do so.
7. Close Impulse
8. Copy all files from the first download (Crossroads) into the Armored Princess folder that you just downloaded. Overwrite all files
9. Launch Impulse. Crossroads now works properly.