Banks are Asset because they reflect Funds. That isn't what you are asking about. That is Source of Spending. Not the Why or the Reason.

"Until checks are issued, how can I show it as a liability?"

You keep skipping the entire Why or Reason. You keep focusing on Banking, but banking doesn't just happen. Banking is happening Because of something else. What is your Something else?

Is this what you are asking: We need to Enter a Bill for medical services expense, that we need to pay from this specific bank account,  and Enter bill = to show I will pay it later. That means the Liability = AP.

Or, I know we committed to $x as HRA per employee and I am an accrual basis entity, so I need to put $x from Operating Bank into HRA Bank and show this is Liability, which the movement of Funds cannot be Both things at once. It is a Transfer (asset = asset) and then HRA is the Reason I would also enter an Expense offset to Liability = accrual basis expense means you never paid it, but are carrying it as Expense. You pay out Liabilities on the Check entry. Then, at year end, you might 0 out Liability back into Expense, to reduce expense for Funds not Spent that year.

You need to map it out; where is the Reason? Not the Funds. We know where the funds are = in a Bank account, which is an Asset and will be the Source of the Spending to meet the requirements of that reason.