MS Windows 10 Pro x64 Intel Kdenlive 16.12.1 beta for MS Windows + FFmpeg download per instructions on https://kdenlive.org/download/ Via Menu->Project->Add Clip or drag&drop get 'Invalid Clip' complaint. See bug 375278 for 'Invalid Clip' issue. THEN, Project Bin retains the invalid clip even though Program indicated it would be removed. Right-click on Bin item shows Delete Clip action is available, so select it. Invalid item does not disappear. Right-click on item again and Delete Clip action no longer available. Screenshot attached.
Created attachment 103520 [details] Screenshot of Project Bin with phantom item
Please try with the actual Kdenlive version 18.08.1