I can confirm this for at least 3 full UBRS runs. All the time i was the only one feral in the raid, and no other class experience the same problem.
(and this is not the same bug as "untargettable" mobs in ubrs, this is a completly different story ... but with this 2 conjuncted bugs UBRS is a most annoying place for me)
I haven't face this problem at any other place ... before few days ago i've notice it on Warsong Gulch - i wasn't able to hit a human priest for ~1.5 minutes of "attacking", and all my "Maul" attacks were "Interrupted". Even if the priest was holding still for a 10-15 secs at one place. and i was trying to attack him from different angles\distances.
So i want to know if any other player can confirm this bug, so i will try to report in on bug-tracker (still don't know how, and at which directory it might be reported though

//edit For me, problem was caused by sRaidFrames_Improved addon. There is an option for accurate rangecheck, which is automatically recheck all the raid frames several times per second, and supposed to be used only for healers. When you switch the check to "light" problem should be solved.