At 20:22 Beijing time on July 28, according to the Kraken status page, the Kraken App's Instant Buy feature experienced an issue with available balance display. Some users' balances may show as 0 EUR or the equivalent of 0 in other fiat currencies. Kraken stated that a fix has been implemented and they are monitoring the results. In the meantime, users can use the Instant Buy feature via the official website.