Older source
From The Lost Media Wiki
The June 1963 issue of Famous Monsters of Filmland, available as of writing on archive.org, features a lengthy article about different stage and screen versions of Dracula. On page 43, we get the following sentence with no further elaboration:
"Eric Jason, specialist in stage monsters, once told me he was sure there'd been a Russian version of DRACULA."
Hardly any better evidence than what's been posted here before, but might be a good candidate for where the rumours began.