I've recently done a couple of 1080 projects in Motion 4 involving camera moves past vector shapes (be they Motion-generated text, or downloaded vector images). During the course of the moves the vectors end up being scaled very large when they're close to the camera.
Everything's fine until I switch on motion blur and render, at which point you can guarantee that there will be corrupted frames at the points where the vectors are being majorly scaled up. Leave motion blur off, and no problems, but I really want it switched on!
I've tried playing with the amount of blur, and with lower settings there are fewer corrupted frames, but it's impossible to eliminate them completely other than by switching off the blur. I've trashed the prefs and tried rendering to various different codecs, and the results are always similar.
Any ideas? I'm suspecting something to do with the amount of graphics RAM available to Motion, but since I'm working on an iMac, there's no way of increasing that.