I used HackMd for months in my work, my email account associated with the service went through a migration process but the same email was kept, all other services were migrated correctly and I had no problems, except HackMd which for some reason created a new ID and overwritten my old account with a new account. The result is that I lost all my important documents. I contacted support and got no response. I have currently migrated to another service, do not trust the security of their cloud service