Hello there,
my Canvas needs to be set active manually in order to work correctly.
Let me explain this. I programmed my Canvas having it active all the time. I gave it to a college, so he can incorporate it. (YES, we do not use version control (sad face)). He just enables it by script and all the child-elements get spawned (so the script execution works, but they are not visible on the canvas). One has to disable and enable it manually in the editor for it to work.
It is also possible to have it active on launch and disabling it manually. After that enabling it by code works just fine.
This is confusing. Pleeease help me ooooout, it would be appreciated soooooo much (kinda happy face).