Same issue for me, many years worth of data in Producteev.
I've started exporting out my teams data from Producteev (daily backups) and porting to a free Asana account as a backup when I can.
It's not ideal but better than nothing!
There have been no replies to my emails, Twitter DM's or here on this community.
They said they won't comment but I got a response saying they are done. I would backup immediately.