Swapped the A with another bass (that’s why we need multiples, see?) and the problem has gone! And the donor bass seems happy with the previously problematic string. Win!
I think it may have been break angle related, as I have more windings and a better angle now. The donor bass has teeny little posts, so isn’t a problem there.
Still a touch clicky, but that’s probably my fosters poor technique!
Thanks all 👍🏻👍🏻👍🏻