[GNC] Transaction report

[Fred Tydeman]

OS:  Linux
GnuCash 4.13
Default currency: USD

I am doing a Transaction Report for one account that is in COP for last
year.
Each month, I receive a fixed amount of COP.
In the Options for the report, in Currency, I have checked both
Common Currency and Show original currency amount.
The Report currency is USD
The price source is Last up through report date.

In the report:
The Debit column shows the same amount each month (as expected).
The Debit (USD) column shows different amounts each month.
If the price source were based upon report date, I would expect the USD
amounts to also be constant.

Perhaps, the price source is Last up through <<Transaction>> date.

Also, is Report date:
  Date I run the report (today)?
  End date (in General Option)?
  Something else?