It could also be an issue with your account. Sometimes an account requires an agent to reauthorise it as being fine to book redemptions from.
I had a similar issue earlier this year, when I couldn't book at DL domestic award flight. Ended up calling and the agent had the same issue. Fortunately he knew that sometimes an account needs an agent to reauthorise it. He did that and then booked it for me.
Might well be an issue with LATAM bookings on VS, but I wouldn't discount this potential issue as well, otherwise you may be waiting some time for the wrong fix.