Using a RPi 3B+.
I made a fresh Raspbian for Robots installation on a new 16GB SD card.
Installed espeak using your guide.
When testing Hello world, it is silent in my speaker.
When using the first, longer test sentence, it sounds but some words are missing.
So, I tested my own sentence and the first word is always missing!!!
espeak -a110 -ven-us “So, once upon a time there was a ghost” 2>/dev/null
It never say “So,” nor any other word, if the word is alone.