[4.0.2] Non-base currency is not converted in budget since v4.0.0

I believe this is a new bug since v4.0.0.

When I have a transaction in a non-base currency (e.g. HKD 1,000), it is displayed to have the same value but with base currency as unit (e.g. GBP 1,000) in the main page of “Budgets”. It also messes up the “Available” and “Sum” calculations on the same page.