Yes, a debit balance on 2210 is an asset, and if it’s not showing as such on the balance sheet then the most likely explanation is that you’ve got the wrong date selected on the balance sheet report (which is very easy to do - I’ve never worked out the logic for what date it selects by default).
Where are you seeing the “debit balance at year end”?
If you’re looking at the chart of accounts then the number you see there isn’t necessarily the balance, it’s the net total of transactions on that nominal in the period you’re looking at. An account might show +£XXX in the chart of accounts but if that account had a balance of -£XXX at the period start then the actual balance at the end of that period would be zero (and it won’t appear on the balance sheet at that date). The trial balance report might be a better place to look than the CoA.