There is currently a technical issue affecting the transfer of points from Avios to BA. I just tried. The points left my Avios account (now 0 balance) but I got a message saying they could not be credited to my BA account and that I needed to contact Avios to have them credited back to my Avios account! I did that, but the agent said:

"There is currently a problem with the transfer function. It has been reported to the BA and Avios online teams who are working on it. If points have left your account they will roll back within 24 hours."

So be cautious about trying to transfer points until this problem is fixed. It is apparently "being investigated as high priority". But this is BA IT we're talking about, so that could mean anything!