In fact, I opened the form that isn't working, removed a lot of it's fields programmatically (using jQuery) and tried again. It worked.
Is there a certain amount of fields for which chrome's autofill stops working?
Could this be a bug?
I tried with Firefox 42 and it was able to remember the submitted values and show the autofill with the correct suggestion afterwards.
+rouslan@ who might know something about autofill (or the right people to CC).