What version of VP is being used?
In the POSITION effect, click the two squiggly-lined icons, to show the graph.
If the line has a slope, instead of a straight horizontal line like this, right-click in the graph area and Delete All Keyframes.
Click to enlarge
Now program your effect.
In the coming weeks, when a new 14.x release arrives, install it and the issue may be resolved. For licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee is required in order to register the newest. Retain your old install file and registration info. If there's an issue, you can always revert.