The current DBZ.space Dokkan Battle APKs appear to have a problem/bug. After the transfer, the app shuts down and all of the account data gets lost during this process.
Please download and install Dokkan Battle Japan from the QooApp APK and Dokkan Battle Global from the Google Play Store until this problem gets fixed. Thank you!
After your first transfer to one of the original apps, you can link the account to your Facebook account and try transferring it to the dbz.space APK. This way, you won't lose the account even after the app crashes.