Describe the bug
All php function and class output an errors
To Reproduce
all of php basic function (preg_match, parse_url, etc) reproduce errors
Screenshots

Platform and version
WINDOWS 10, VSCode 1.41.0, PHP Inteliphense 1.3.3
Have you changed intelephense.stubs setting? Looks like is missing core stuff.
Another thing to try is to re index the workspace. ctrl + shift + p -> Index workspace
i had paid the license. and that's still not work. after VS Code Update to 1.41.0.
i have same issue all my controller get error like this "Undefined type 'CI_Controller'.intelephense(1009)"
Undefined type ''.intelephense(1009)
that's happen when i open the file php.
i have try Index workspace still not work.

i already ctrl + shift + p then index workspace, all basic function fixed but not my class, i mean : my class function not indexed and output error like this.
and all my namespace from composer vendor folder, output an errors too

class description and function description is working on peek but also output errors too

now loop indexing :( and made disk usage 100%
Does it finish indexing? Once it finishes it should refresh the diagnostics. How many php files in the workspace?
Done with simple tricks.
downgrade vscode intelephense, reindex, then update to latest version again, then reindex automatically.
Most helpful comment
Another thing to try is to re index the workspace.
ctrl + shift + p->Index workspace