There's a major Inland Revenue systems upgrade occurring this month in April. Their offices, phone lines and online services (including myIR) will be unavailable from the afternoon of Thursday 18th April 2019 until the morning of Friday 26th April 2019.
So what does this mean for you as a PayHero user?
Payday returns can't be filed during this time, so they'll be queued in PayHero and filed automatically when the IRD reopens. In the meantime their status will be shown as 'Pending'. There's no need to worry, as any returns due during this period can be filed on Friday the 26th April 2019 without incurring penalties.