I'm running a clean install of Sonar Platinum on a new machine.
I've discovered that the "From=Now" CTRL-F6 and "Thru=Now" CTRL-Shift-F6 don't work.
They work fine from the menu, but not the keys.
I checked in Preferences and the Keyboard Shortcuts setting shows those keys are assigned as CTRL-F6 and CTRL-Shift-F6.
CTRL-A for select all and CTRL-Shift-A for select none seem to work, as well as CTRL-V, CTRL-C, CTRL-Z and other keys.
 
Why would CTRL-F6 and CTRL-Shift-F6 not work?
 
 

I recall there being problems with these shortcuts when they were first introduced in X1, replacing the longtime defaults of F9 and F10. As a longtime Cakewalk/SONAR user, I restored the older defaults (along with Ctrl+F9 and Ctrl+F10 for From=Beginning and Thru=End) and never looked back. Not in front of my DAW right now to check the default bindings in Platinum.

I went ahead an re-mapped to new function keys for the select like you did.
 
Interesting note - it is impossible to unbind CTRL-F6 and CTRL-Shift-F6. The keys are bold, and indicate the binding function below, but unbind just causes the error sound.
It may be that the bindings are incorrect - the default binding showing for CTRL-F6 is "Set From=Now"
The actual text for the function in the right column is "Edit | Select | From = Now"
There is no function for "Set From=Now"