Balance Sheet - Link credit card accounts to show one line
Xero imports separate feeds for cardholders of the same credit card account. The payments will show on only one of the feeds, resulting in the balance reflecting as an asset and the rest of the accounts as liabilities.
There should be a way to link the accounts together so the merged balance shows on the Balance Sheet as one liability.

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Daniel Bland commented
There are third-party tools - like RecHound - that can do what you are asking, by providing grouping of accounts.
Quick video here highlighting the features:
https://www.rechound.com/video-demoIf you like it, you can link it to your Xero and start a free non-obligation trial here:
https://app.rechound.com/starttrial -
Aiza Manapeng commented
Also, credit cards should always show as a liability in the balance sheet regardless if it's positive or negative instead of customizing the report.