Capital Gains Real Time Transaction refused (didn't include my calculation?)

After waiting for a few weeks I got an email response:

"Thank you for sending me the 2025-26 Capital Gains Real Time Transaction. Unfortunately, we are unable to accept it. We cannot accept this submission because the computation you sent us did not show how you arrived at the tax due.   

Your calculation must include a full breakdown of how you have arrived at your gain and tax due including details of tax rate used and any reliefs you might be claiming."

I filled out all the numbers in their boxes so the maths checks out and also sent a screenshot from koinly showing the numbers again including my costs, income, profit etc.

What did you guys include in yours to get through? Am I supposed to start a little document writing out my maths again and how I calculated it myself? I'm confused since they have all the numbers already.

Would I just write Costs: xxx Gains: xxx Profit: Gains - cost = xxx (profit) Profit - CGT allowance = Taxable profit etc? It feels like such absurdity.