Obvious question first. Are you tilting the camera properly?
Are you on Xbox?
Had a similar issue and fixed it by switching to a new game then restarting Fallout.
Seems linked to the resume function.
if it is xbox.... You need to unplug the console for atleast 1 minute... this clears out the cache. Then boot it up and try it again. If the problem persists, quit the game, unplug the console again for 2 minutes, boot up a different game and then go back to fallout.
I just recently found out about a very useful positioning trick ---- if you have the object visible, but red so you cannot place it, you can HOLD the Activate key (whatever it is on a console) and then you can move the mouse around smoooothly. You can also use the mousewheel (or however you "mousewheel" on a console) and it will raise and lower the object. Could kick myself for all the time I wasted before I discovered this way of positioning.