I would agree with Tim. Having bought the first version of 11, I noted that it was very buggy in respect of retaining the correct keyframe information over a number of plugins.
The obvious thing to check first is that you have the latest version of the software (Build 510 for the 32 bit version and build 511 for the 64 bit version). If not, then download the latest version. To be fair to Sony they have addressed a good number of these issues in these releases. Otherwise I think you have to report the problem to Sony as a bug.
Good luck in resolving the problem.
COMPAQ something or other with 500Gb Boot Disk, 1Tb external Firewire Disk, 4Gb Memory and a super duper sound card, 19" TFT Monitor etc etc etc
Sony TRV33e : Sony TRV310e : Canon XM2
Sony Vegas Studio editions to v11
Remember, there is always more to learn than there is to teach.