I think I have come across this problem before, but right now I'm seeing it in the Vegas effect. The rotation parameter inside this effect only goes as far as 91 cycles. Anything over 91 and it just stops. While for certain applications the layer's rotation can be used, and that one doesn't seem to have a limit, for other uses it can't since it changes the look of the effect.
Is there any way to overcome this problem?
I haven't had to push Vegas that far, but can't you type in the number of cycles you want?
I just tested the Vegas effect and you're correct, the Rotation value stops having an effect at 91 rotations + 8 degrees.
Please file a bug.
This is likely a result of the maximum memory size allowed for that parameter. 91 (rotations) * 360 (degrees) = 32760. Add 8 (degrees) and you get 32768, a rather common number in software (2^15). There's no particularly good reason why we couldn't increase that. If you find other effects with the same limitation, feel free to file a bug about those, too.
I have a workaround suggestion, though I don't know if it will work for you or not, it depends on what you're trying to do. Duplicate the layer and on the duplicate, move the Rotation parameter to a much lower value and adjust the Vegas parameters so that the appearance of the effect is the same as it was at 91x8. Then adjust the layers in time so the duplicate layer is visible where the old one reached 91x8.