Invoice balances dropping to zero - anyone else with the same issue?

I am raising invoices in QB and within half an hour the balance has been dropped to zero. It is being investigated by QB and they have no idea why it is happening. I can't be the only one that this is happening to!

Obviously this is impacting our debtor balances, matching bank payments and our VAT return. It is having a huge impact on our business and the issue is now with the Tier 3 team. Has anyone else experienced this and what did you do to resolve it?