[solved] Why bitcore call getBalance answers 'undefined'?

For some reason bitcore answers ‘undefined’ to ‘bitcore call getBalance [address] true’, when all transactions for this address are confirmed and shows actual balance before last transaction confirmed.
How to fix it?

Bitcore says ‘undefined’ to getBalance calls until full database sync is done.
‘bitcore call getBalance [address] true’ still works, but only for unconfirmed transactions.