lsp-ui-sideline no diagnostics

[BossCode45]

I am using the clangd c++ server with this file

#include <iostream>

int main()
{
	cout << "stuff" << endl;
}

I have the following config for lsp-ui-sideline changed: lsp-ui-sideline-update-mode line, the rest is default
this is what i get when i hover the line:

with show-hover turned on to check if it works:

Flymake is able to find the errors and will display them:

It doesn't matter what the error is, it never seems to display

[BossCode45]

Nevermind, I hadn't installed flycheck.