This problem doesn't seem to be version specific - I've tried CS4 and CS6, and the problem acts the same.
I'm using a Samsung ATIV 700t, which has input through touch screen and Wacom digitizer pen. Using any tool (ie: brush) on the stage with the pen results with the start position recorded and only detecting another position when the pen leaves the program area. Brush and pencil toos will show a dot at the start point and create a straight line to the exit location. When I use touchpad input things work as expected - I can draw without pressure sensitivity, provided I wait as to not trigger panning functionality.
You have 2 major hurdles.
#1, does your Wacom tablet explicitly declare it supports Windows 8? This means completely. Not just pen down, pen up. This means pen down, up, pressure, etc.
#2, does Flash understand your drivers inputs on Win8.
Win7 has support for touch input. Have you tried this tablet with the limited touch interface support on Win7 to even verify if Flash supports it?
#1 - Wacom's Digitizer board is what is used in most tablet PC screens that support pen input. This is what Samsung uses, despite the fact that they call it an "S-Pen."
I had been using Wacom's latest Tablet driver (7.1.0-8) which was the only option under Windows 8. I downloaded the previous version for Windows 7 (7.0.9-5), and it seems like the problem is resolved. Photoshop and Flash now work, other desktop apps continue to work, but Windows 8 Metro apps don't. Oh well.
Thanks so much for this. I had the exact same problem on my Lenovo ThinkPad x220 tablet using Flash CS5. I rolled back to the Windows 7 (7.0.9-5) Wacom driver and it works again. Whew!
(Side note: Illustrator CS5 worked great with the lastest driver. It was just Flash that had this problem. Hmm.)