The customer has a issue as - When generate project invoice proposal, -ve amount of Billing rule A loaded but user did not select that Billing rule originally.

we did raise a BUG # 752828 as it was replicating in standard environment.

PG team provided update as its at this time it is believed that this is working as "By design".

in future please enable this feature to show as expected values as how it was in previous versions.it will help customer.