xdebug connects but won’t break in WordPress with vvv

In my case it turned out to be a path mapping issue. Adding…

"pathMappings" : {
    "/srv/www" : "C:\\Users\\tmorgan\\websites\\local\\www"
}

…fixed it for me. In other words, explicitly specifying how the server path related to my local file path was necessary. I did not think this was the case because xdebug was connecting to my client, but connecting is different from successful file mapping.