Sage VAT transfer and PVA

I am just tidying up for the year end and I have two weird balances on the Purchases and Sales tax control account. 

The Purchases Tax control is a credit balance and the Sales is a debit balance - which is strange for starters - and the amounts are very similar.

After a trawl through the transactions for both accounts I have reconciled the balance on the purchases tax control account and the problem is the Sage transfer figures for Q1 & Q2 in 2021 - the transfer figure includes the PVA for those two quarters (which should not be in the transfer figures as Sage already brings the purchases tax control to zero by the double entry used to record T18 purchases).

The error had stopped by Q3 and has not been repeated in Q4 (which is co terminus with our year end so normally an easy reconciliation).

Has anyone else experienced this?

If Sage issued an update to correct this anomaly where will I find the documentation so I can prove to HMRC that I'm not making this up?

Thank you.