I'm testing the new Super Scale feature but it seems there is a problem with interlaced footage when "Enable video field process" is checked.
As you can see from the video below, if "Enable video field process" and Super Scale are both enabled, the video is half height.

DaVinci Resolve 15 Beta 2
Source video format is MP4, 720x576 25fps Upper field
Tested on two systems:
- Laptop: Windows 10 Pro 1709, CPU Intel i7 3650, RAM 16 Gb, GeForce 750M
- Desktop: Windows 10 Pro 1709, CPU Intel i7 6800K, MB Asus x99-E WS USB 3.1, RAM 32 Gb, GeForce 970