Firstly - please do not create duplicate threads on the same topic - it fragments any replies and also breaks the forum rules. Your duplicate post has been removed.
Secondly, have you read the Help on WalkThrough Mode?
"E" (or Shift+UpArrow) is Up, "C" (or Shift+DnArrow) is down.
You can look anywhere using Ctrl+LMB, or lock the vertical motion by pressing the Spacebar (to maintain "eye level"). These all work perfectly here, so Max is not the problem.
Note that you
must have the Keyboard Shortcut Override Toggle turned on or many of those keys will not work as expected.
Finally, if nothing above helps, you might consider unloading any drivers for the G15. Logitech drivers have been known to cause problems in the past, though I've seen very few such instances with recent versions. Worth a try as a last resort.
Max 2016 (SP1/EXT1)
Win7Pro x64 (SP1). i5-3570K @ 4.4GHz, 8Gb Ram, DX11.
nVidia GTX760 (2GB) (Driver 430.86).