Cost Assignment Change on Header Level

Question

This User changed the cost assignment at the top level to an internal order;
however, it did not apply to one of the hotel charges.
The other charge on the same date for the same vendor did change.
What caused the one transaction to remain with a cost center instead of internal order?
It was our understanding if the User changed the cost assignment at the top level it would be applied to all transactions in the report.  Is this not correct?

Answer 1

Got the Solution from Development Colleagues:
If a traveler change the cost assignment from cost object A to cost object B at the top level of an expense report, then all expenses which are assigned to the cost object A at change moment(!) should get the new cost assignment to cost object B.
All expenses which are assigned to a different cost objects as A will be not changed!
Example 1:
Step 1. Traveler created an expense report with the cost assignment to cost center A
Step 2. Traveler added 3 expenses
=> Expected result: all 3 expenses should get the assignment to the cost center A
Step 3. Now traveler changed the cost assignment on top level of the meeting request to the project B
=> Expected result: all 3 expenses should get the assignment to the project B
Example 2:
Step 1. Traveler created an expense report with the cost assignment to cost center A
Step 2. Traveler added 3 expenses
=> Expected result: all 3 expenses should get the assignment to the cost center A
Step 3. Traveler changed manually the cost assignment of one expense to internal
order D
=> Expected result: 2 expenses are assigned to the cost center A and one expense is assigned to the internal order D (because of manually change!)
Step 4. Now the traveler changed the cost assignment on top level of meeting request from the cost center A to project B
=> Expected result: only 2 expenses which were assigned to the project A are now assigned to the project B, the one expense which was assigned to the internal order D should be still assigned to the internal order D (it is not assigned to the cost center A and therefore not affected by the change from cost center A to project B).