It sounds like there is a plugin interfering with the CtrlU undo option. To find it, open the console with Ctrl` and enter the command

听起来像是有一个插件干扰了 ctrl / lu 撤销选项。 要找到它，用 Ctrl 键打开控制台并输入命令

sublime.log_commands(True)

This shows what's going on behind the scenes when you press key combinations or use mouse buttons. Test it by making some multiple selections with CtrlD, and you should see

这显示了当您按下组合键或使用鼠标按钮时，幕后发生了什么。 通过使用 ctrl 键进行一些多重选择来测试它，您应该会看到

command: find_under_expand

in the console. Now, try to undo one of your selections by hitting CtrlU and see what comes up. If you see

在控制台。 现在，试着通过点击 ctrl + lu 来撤销你的一个选项，然后看看会出现什么。 如果你看到

command: soft_undo   我看到是 run_emmet_action : update_image_size    
 所以我增加了一个快捷键 alt+shift+j 的 command 为   soft_undo   就可以了

 	{ "keys": ["alt+shift+j"], "command": "soft_undo" },

then it's not another plugin issue, as that's what you'd expect to see. However, if (as I suspect) another plugin is interfering, you'll see something else there. If you do, hopefully you'll be able to trace it to the plugin it belongs to and disable it.

那么这就不是插件的问题了，这就是你所期望看到的。 然而，如果(正如我怀疑的那样)另一个插件在干扰，你会看到其他的东西。 如果你这样做了，希望你能够追踪到它所属的插件并禁用它。

When you're done, enter

完成后，输入

sublime.log_commands(False)

in the console to turn logging off, then close the console by hitting Esc or Ctrl`.

在控制台中关闭登录，然后按 Esc 或 Ctrl‘关闭控制台。