How cut in TCC tab window

If I have a Take Command tab window running TCC, how do I cut text using the keyboard? I see the Edit > Cut menu item. Hovering says the keyboard shortcut is Shift-Del. But, if I use the keyboard to highlight text on the command line, "Cut" is dimmed, as it is if I right-click. Pressing Shift-Del does nothing (both for the Delete key and Del on the number pad). If I highlight text with the mouse, it is still dimmed.

If I run TCC in its own window and select properties, I have "Enable Ctrl key shortcuts" and "Extended text selection keys" unchecked, if that matters.

TCC 20.00.21 x64 Windows 10 [Version 6.3.14393]
May 20, 2008
Syracuse, NY, USA
I am trying to cut text on the command line. I type some text. I cursor left. I hold down Shift. I cursor left some more. The text is highlighted. Now, how do I cut? Shift-Del does nothing. "Cut" is dimmed in the menu.
Same experiment here ... Win7/32 ... both Shift-Del and the menu's "Cut" work.