Reproduction steps: 1. Open https://jsfiddle.net/Comandeer/s2b0nu3v/ 2. Click on the buttons below the table. Expected result: Selection in <thead> should behave the same as in <tbody>. Actual result: Selection in <thead> seems to be broken – trying to select the last cell selects the whole row, except the last cell and trying to select the whole row does nothing. Additionally, trying to select the last cell in <tbody> also selects the whole table except the last cell. It works correctly in both Chrome and Firefox. Selection in <thead> is also partially broken when using Selection#selectAllChildren: https://jsfiddle.net/Comandeer/s2b0nu3v/0 – in this case selecting the whole row in <thead> doesn't seem to do anything. Safari version: 14.0 (15610.1.28.1.9, 15610) Issue wasn't present in Safari 13.x. Original bug report in CKEditor 4: https://github.com/ckeditor/ckeditor4/issues/4306