Is it possible it's coming up, but beyond the borders of your screen? Of course, there's probably no really way to determine this, but might be the case. You could try looking in the user settings file
C:\Users\<Replace With Your Profile Name>\AppData\Roaming\Smith Micro\Anime Studio Pro\10\Anime Studio Pro10.user.settings
Look for:
"ActionWnd_Open" "TRUE"
then also look for:
"ActionWnd_location" "1302 497"
the first number is the left to right pixel position of the window, and the second number is the top to bottom pixel position
"ActionWnd_shape" "256 256"
I believe these are the height and width of the window
i had the same Problem. i worked with a surface and the Resolution was set to show the letters bigger. and in as the Action window didnt appear. due to the help of someone from Smith micro i changed the Resolution (high Resolution) and in as the Action window appeared