Mount offset / setLinkPoint

I'm trying to change the mount point of an object that is already mounted to another. Calling setLinkPoint appears to have no effect. Where %id is the link point returned from mount(), I've tried calling setLinkPoint(%id) and then echo()'ing there results of getLinkPoint(%id) and no matter what the results are always "0.000 0.000"

Is this incorrect or a problem with TGB? I'm using 1.7.4 because I only have the binary license and I need to use PSK.