Swing well in practice but falls apart on course

I can hit the ball reasonably well on the range, but then on the course I struggle to even make decent contact — topping it, especially with driver.

I've recently had a lesson working on connection between chest/arms/hands and stopping my takeaway getting too inside. I can sometimes get it working nicely in practice, but then it disappears when I'm playing.

Anyone else had this? How did you get your range swing to transfer onto the course?