The WBS Sort ID value does not automatically update after moving tasks in the Modern User Experience (UX) Task Timeline. You will see two tasks with the same WBS Sort ID
Clarity 15.9.2, 15.9.3, 16.0, 16.0.1
Workaround: Refresh the page or click on another module then return to the Timeline
If assistance is needed with this issue, contact Broadcom support.