I had the Kanban view open in a browser tab (see start.png), and was updating an artefact on another tab (via its link, not a modal).
When I switched the artefact to "Scheduled", the kanban page was updated but showed all scheduled artefacts on top of the masked column (see result.png).
(Reloading the page fix it)
Original art moved https://my.enalean.com/plugins/tracker/?aid=117301 showing issue on https://my.enalean.com/kanban/15
also tried with https://my.enalean.com/plugins/tracker/?aid=117955 it only happened while "Submit", not while "Submit and stay", but not each time so not a clear reproducible procedure...
Firefox 139.0.1