Do I think that cost her votes?
Well, no, actually.
Most Democrats didn't give a bloody toad fart what Hillary had or hadn't done.
Those who supported her likely did so right through to the end.
I think there were plenty of pee-ohed Berners out there still ticked that she had finagled the nomination, and that might have hurt a little in enthusiasm for GOTV efforts.
Neither side had their most massive turnouts, implying large unhappy factions on both sides, and overall, the other ('third') parties gained support, perhaps out of Republicrat fatigue.
These were ordinary Clinton dirty tricks and cheats, and a meeting between the AG and Bubba would be expected by those who thought she'd make a good POTUS.