Tested with emacs -Q with those settings

(setq corfu-auto t)
(setq corfu-auto-prefix 0)
(corfu-mode +1)
(corfu-prescient-mode +1)

Currently, corfu-prescient--remember doesn't add corfu-insert candidate to prescient--history. It might be related with this line:

After I use this hack:

(advice-add #'corfu-insert :before #'corfu-prescient--remember)

corfu-prescient--remember seems to work normally.