Shared Tabs: Adding custom bill 100% to one person does not update total

Issue: When adding a custom bill to a shared tab (of 2 people) and setting the whole payment to one person then totals owed at the top do not update.

Details to reproduce:
Have a shared tab with 2 people with a balance against each person at the top. (£-880 and +£880 in my example) (Screenshot 1)
Add New payment > Add custom bill > enter amount (£88 in my example) (Screenshot 2)
On the “Split Bill” page set all the money to one person (£88 to one and £0 to the other)
Click add Bill (Screenshot 3)
Notice that in the shared tab the new payment is showing but the balances at the top have not changed and still says I owe £880 when in fact it should be £792. (Screenshot 4)

OS: Android 11
Device: Pixel 4XL
App Version: 3.80.0

Screenshots: