I've prezto and on urxvt moving the cursor backwards makes it disappear, and you can only see your position from the letters color changing to the cursor color when the cursor is on them. this doesn't happen while text editors or while using bash. This happens both in command mode and insert mode (while vi commands are enabled), both without and with the editor module enablad.
I think this depends on your settings regarding prezto:module:syntax-highlighting in your .zpreztorc. If you activate highlighting for cursor you get the behaviour you encounter. If you disable cursor you shouldn't.
zsh-syntax-highlighting is buggy. It's not the same quality as syntax highlighting in the fish shell, and it will never be until it's rewritten natively and integrated into Zsh. Enable highlighters one by one to see which ones cause you problems.
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I think this depends on your settings regarding
prezto:module:syntax-highlightingin your.zpreztorc. If you activate highlighting forcursoryou get the behaviour you encounter. If you disablecursoryou shouldn't.