Yes you get it back but it's a hassle. I did the refunds via the phone for a while and it typically took ~15 min per request. I switched to email and about half of them go through without an issue, the other half get "stuck" and require a call. Last call I was on to reconcile this was nearly an hour. The other hassle is if you want to pay cash for the main seat and points for XS, it requires a call. My situation is complicated by the fact that I have CP, so sometimes there is a third seat involved. I found a bug in the system which was reconciled by adding the XS before booking CP. However that seems to have changed, for the last several flights I've had to speak with gate agent to reconcile.

At this point if I could just buy an extra seat and avoid the hassle I would. No sure why, but Southwest doesn't allow this.