I'm using selenium to write a test.
I check an element text is equal to what I expect.
It was working, I change stuff, it break.
Nothing new under the sun.

I debug my code. Element text is empty. I forgot to run with a browser window so I ask selenium for a screenshot. Element look as expected. I recheck the element text. It changed.
I assume it's a timing issue but waiting 15s have no effect. Meanwhile, asking for a screenshot, not even saving it, get the correct text.
I don't get it.