Visual Studio Code waiting for second key of chord. (Ctrl + A)
You might be in a situation where you want to keep the chorded keybindings that are causing you the problem with your original keybinding. A potential workaround to this issue is turning your original keybinding into a chord as well. For example, you could having a 'stop' character that exits your chord. For example, "Ctrl+A ." where "." is your stop character.
So if for some reason you really liked "Ctrl+A" as the beginning keystroke for a bunch of chorded keybindings, then rebinding all current "Ctrl+A" keybindings to "Ctrl+A ." would free up that keystroke for any manner of other, chorded keybindings.
You have another key binding that begins with Ctrl+A, something like this:
A sequence of multiple keystrokes pressed one after another (rather than simultaneously) is called a "chord".
You might have accidentally created it, or might have recently installed an extension that adds the problematic binding. To find it, do like I have done in the screenshot and type "ctrl a" into the Keyboard Shortcuts search box (that tab can be opened by typing Ctrl+K then Ctrl+S). Then look for a binding that begins with Ctrl+A but has something else after it (in my case, another Ctrl+A, but it could be almost anything).
When you find the offending binding, right-click on it, and either remove or change it. Then Ctrl+A alone will resume working.
Note: This question and its answer pertain to Visual Studio Code, which is different from Visual Studio. See this question for information about the equivalent situation in Visual Studio.