Robin Darlington

I was able to fix it myself in the end, using woocommerce_form_field_args filter :

add_filter( 'woocommerce_form_field_args', 'belair_vat_woocommerce_form_field_args', 10, 3 );
function belair_vat_woocommerce_form_field_args( $args, $key, $value ) {
	
    if ( $key == 'billing_eu_vat_number' ) {
		$user_id = get_current_user_id();
		if($user_id){
			$ws_vat_no = get_user_meta( $user_id, 'wwlc_cf_no_tva', true );
			$eu_vat_no = get_user_meta( $user_id, 'billing_eu_vat_number', true );
			$uservatno = $eu_vat_no ? $eu_vat_no : $ws_vat_no ;
		}
		if($uservatno){
		  $args['default'] =  $uservatno; 		
		}
    }
	
    return $args;
}

After a bit more investigation:

– this issue appears from ACFE version 0.8.8.8.
in version 0.8.8.7 it still works as expected. I have downgraded to that version for now.

– it also seems to appear the same in previous versions of ACF and WordPress (tested WP v 6.0.1 and ACF all the way down to 5.12.3).