카테고리 구조를 설정하기 위해 드래그를 하면 에러가 뜹니다.

클릭해서 조금이라도 드래그하면 파란 점선 사각형 리스트가 쭉 늘어나버리고 개발자 도구에선 저런 에러가 뜹니다.

제가 뭘 잘못하고있는걸까요?

sortable.min.js:9 Uncaught TypeError: Cannot read properties of undefined (reading 'left')
    at x.<computed>.<computed>._refreshItemPositions (sortable.min.js:9:12843)
    at x.<computed>.<computed>.r.<computed> (core.min.js:116:958)
    at x.<computed>.<computed>.r.<computed> [as _refreshItemPositions] (core.min.js:116:958)
    at x.<computed>.<computed>.refreshPositions (sortable.min.js:9:13038)
    at x.<computed>.<computed>.r.<computed> (core.min.js:116:958)
    at x.<computed>.<computed>.r.<computed> [as refreshPositions] (core.min.js:116:958)
    at x.<computed>.<computed>._mouseStart (sortable.min.js:9:2132)
    at x.<computed>.<computed>.r.<computed> (core.min.js:116:958)
    at x.<computed>.<computed>.r.<computed> [as _mouseStart] (core.min.js:116:958)
    at x.<computed>.<computed>._mouseMove (mouse.min.js:9:2340)