Hi! gMKVExtractGUI 2.4.0.0 mkvtoolnix 28.2.0 (x64) Win 7 x64 Ultimate If one item is selected, there is no problem. https://i.imgur.com/uFztT6V.png If two or more items are selected, then an error. https://i.imgur.com/forsNZd.png https://i.imgur.com/BXDaUU6.png