Loading a font in a startup_system causes text rendering problems.

## Versions

rustc: 1.58.1 stable
Bevy: 0.6
OS: MacOS Monterery 12.1

## What you did

I was trying to change normal systems and startup systems to instead use states. So I replaced most of the `.add_system` and `.add_startup_system` with the `.add_system_set(SystemSet::on_update` and `.add_system_set(SystemSet::on_enter`.

Everything worked properly before but after using states all the `Text`s became frozen. By frozen I mean that they stayed the same text as I initialized them with. Even though the code was correctly changing their content.

It seems to require quite a few pieces to trigger this behavior but I managed to boil it down to this:
https://gist.github.com/pYtoner/16c2638c5f147be783e2871bbf03a1d3

In the gist, the text should say "working". But instead, it says "not working".