Mixed booking not checked. When adding a resource and choosing Remaining Only, then edit the % Allocation on the Staff Page, then Allocation value does not recalculate and the allocation segment is not set to the new %.
Steps to Reproduce:
Assumption: Admin Tools > Project Management > Settings > Allow Mixed Booking is not checked.
Expected Result: The Allocation to recalculate to 8 hours.
Actual Result: The Allocation stays at 32.0 hours. The Default Allocation changes to 20%, but the segment stays at 80%.
The business rules, through the use of "Remaining Only", locks in the resource with an allocation equal to the remaining only percentage.
This is done by adding a segment on the allocation curve equal to the project start/finish with the remaining allocation percentage.
Changing the "default allocation" means that any allocation outside of what's "locked in" will have a new percentage. There is no allocation that fits this and therefore you don't see a change to the allocation when you change the default.
To make the allocation change in this scenario you can change both the default allocation and the segment allocation percent.