Hello,
It would be interesting to know how the vendor account is create exactly and what are your HikaMarket registration settings.
I suppose that your have some incorrect data into the vendor_acl column ; that something you could check directly in the database (before performing the save in the backend).
Afterwards, I checked the changelog and there is no reported issue with such problem ; but that's not impossible that the latest version contains some fixes which would help since the global code is always improved with the releases.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.