The bug in RC1 is still in RC2, the wacom drive don't find lightroom the specific configuration dont change, if you downgrade to Lightroom 4 all works fine but dont whith the RC's....
Please debug this for the final release
I've heard that Wacom has released a new driver version to address this problem.
I install the latest wacon drivers from wacon us 6.3.1W2 it solved the probleme but you need to recreat all the sorthcut if you restore a backup from the wacon utility thats dont work.
I have recreat the shortcut and all is good, thanks !!!