Most cryptocurrencies have a period of time called “locked balance”, when partial or all funds in a wallet cannot be used for new transactions. It happens after every transaction no matter whether you receive a new transfer or send funds to someone. This way most blockchains prevent spending of funds located in blocks that are not yet “confirmed” by the network. Proof of work blockchains are especially prone to this problem because recent blocks can be “rewritten” by someone who has more computing power. Such a “fork” makes transactions in several recent blocks invalid minutes or even hours after they were initially “accepted” by the network and even added to a blockchain.
Locked balance problem is very inconvenient and prevents adoption by the mainstream. Imagine a situation when you have $1000 in your payment card and you bought something for just $1 but cannot use the card for another hour as the entire card balance is locked by your bank.
Lyra solved the locked balance problem, thanks to block lattice architecture. Since every transaction is written into its own block, and every transaction block is individually and instantly authorized by the network, there is no need to lock any balance to prevent double spending. Once a transaction block is signed by the authorizer nodes it becomes the part of an immutable account blockchain which cannot be modified. The account balance becomes spendable right after authorization response (for any transaction) is received from the network.
See more information about the fork in Why DPoS and how is it different from PoW?