Could you please check if there are any errors at chrome://sync-internals 

I encountered the same issue just after upgrading Chrome 69 to 70, on macOS, with my corp account.
chrome://sync-internals has the same error message.

+vasilii as this seems to be getting worse on MacOS: https://uma.googleplex.com/p/chrome/timeline_v2/?sid=7766898ad049a04e3f3630f1ec83a58c

For Linux M69:
Do you have your Keyring unlocked? Can you open seahorse and see your passwords there?

For Mac M70:
Can you copy the precise error message because the line number should be different.
What's the value of PasswordManager.LoginDatabaseInit and Sync.LocalDataFailedToLoad in chrome://histograms ?

Dominic, In M70 we read the store once, in case of error try to clean it and read the second time. Thus, under some condition the error may be reported twice. Nevertheless, there is almost no data for M70 yet. It's generally growing because the state is not recoverable until M70 (sync users) and M71.

> For Mac M70:

Error: MergeDataAndStartSyncing@../../components/password_manager/core/browser/password_syncable_service.cc:165, datatype error was encountered: Failed to get encryption key during database cleanup.


Histogram: PasswordManager.LoginDatabaseInit recorded 1 samples, mean = 0.0 (flags = 0x41)
0  ------------------------------------------------------------------------O (1 = 100.0%)
1  ... 


Histogram: Sync.LocalDataFailedToLoad recorded 1 samples, mean = 4.0 (flags = 0x41)
0  ... 
4  ------------------------------------------------------------------------O (1 = 100.0%) {0.0%}
5  ... 

That's very interesting, Chrome doesn't get the encryption key stored in the Keychain. Let's try a few things:
- Open 'Keychain access' app. Do you see "Chrome Safe Storage" entry there? What is the access control list for it (basically, if Chrome is allowed to access it without a prompt)? Do you get any error if you try to see the value of this entry?
- If you restart Chrome, does the error persist?

It seems resetting the keychain and rebooting the machine fixed this issue for me.

What error did you get when accessing Keychain?

No errors clicking "Chrome Safe Storage" entry in the keychain.
Attaches a screen short including ACL.
I don't know how to try to see the value.

Deleted: Screen Shot 2018-10-22 at 12.46.27.png 115 KB

	Screen Shot 2018-10-22 at 12.46.27.png 115 KB View Download

Well, now everything works, right? If yes, then we can't answer the questions form the Comment #6.

> Well, now everything works, right?

Right for me.