Don't know about the IB side but BA pulling from IB still appears to be there in the balance transfer tool.
https://www.britishairways.com/trave...club/_gf/en_gb
I don't have any current IB avios although I'm due 900 from Hertz quite soon.
In fact I was feeling brave and moved one avios from BA to IB and then back, and it's all fine.