Hi, firstly many thanks for your work!
I'm facing an issue that there will be no error diagnostics output when I set my output to a subdirectory.
It will work fine when I don't use a subdirectory.

My vscode setting is below:

{
    "texlab.auxDirectory": "latex.out",
    "texlab.build.onSave": true,
    "texlab.build.args": [
        "-pdf",
        "-interaction=nonstopmode",
        "-synctex=1",
        "%f",
        "-outdir=./latex.out"
    ],
    "texlab.server.autoDownload": true,
    "window.zoomLevel": 3
}

Here is the way to reproduce it.

First, create a tex file under an empty directory as

\documentclass[UTF8]{article}                                                                                                                                                    
\begin{document} %COMPILE ERROR                                                                                                                                                  
test                                                                                                                                                                             
\end{document}

Then delete a character to make some error. For example, modify begin to bgin like following, and run texlab builtin "build" command. It will show up "build error" like below, but no error diagnostic is reported.

Besides, when I restart vscode at this time, I will be able to see the diagnostic error but it won't disappear after I correct it. I need to restart my vscode again then it will disappear.

I'm wondering is there any missing in my config? Thank you for your help!