UK MTD reports concerning turnover and cerash accounting

UK MTD reports concerning turnover and cerash accounting

Hi
I am a sole trader, and I have just started with Zoho Books in order to comply with the new HMRC requirements.
I use 'cash basis' - which I understand to mean that income is when the cash comes in (not the invoice date) and expenses are when they are incurred. 
In my first quarterly report, HMRC want 'turnover' - which Zoho takes from the Sales as defined by invoices generated. However, though I generated 30k of invoices in the first quarter, the income from those was only 12k. So shouldn't the turnover as being present in the MTD module be 12k (less expenses). It looks like Zoho is reporting an accrual turnover?

Am I missing something?
THanks
Damien