PREVIEW MAKING NEITHER ARROWS NOR LINES

Hi everyone,

I'm trying to use Preview, as I need to add arrows on a screenshot for university project, but Apple makes it really hard.

Whenever I try to add an arrow on the picture, it does this stupid annoying thing :

I definitely don't know what this is related to, as I used Preview to do this exact same task a few days ago with absolutely no problem, and never faced this issue with the other Mac I own running on High Sierra.

My laptop is a MacBook Pro with Monterey 12.4

Thanks.