Fines charged are incorrect, being undercharged

Overview:

We have noted several cases where loaned items that are overdue and charge a day-based fine undercharge the fine when the item is discharged. Frequently the fine is the equivalent of a day short and is occasionally 2 days short.

Please see the attached spreadsheet for examples. All of the loans represented here were created in FOLIO; they were not migrated. Taking row 2 of the spreadsheet as an example: the item was due 7/19/2021 at 23:59 and was discharged 7/21/2021 at 9:09. Our expectation is that any part of a day overdue counts as a full day, so the item should be considered 2 days overdue. The fine is set to charge $1/day and so should have charged $2. But FOLIO charged only $1. 

If you take a look at row 14 in the spreadsheet there is a discrepancy of 2 days, which is highly significant for this particular fine, since it is set to charge $25/day. FOLIO charged for 2 days when it should have charged for 4.

All of our overdue fine policies are set Count closed days/hours/minutes = No. Could this possibly explain the discrepancy? For day-based loans, we expected that FOLIO would count and charge by day, without regarding closed hours. I changed the No setting to Yes on 1 policy for a few days and after I changed it, it seemed to charge for the correct number of days.

We are on Iris release, HF 2.

Steps to Reproduce:

1. Set up a day-based loan policy, e.g. loans items for 7 days
2. Set up an overdue fine policy that charges by the day, e.g. $1/day and has Count closed days/hours/minutes = 'No'
3. Check out an item with the above policy combination and allow it to go 2 or more days overdue  

Expected Results:

System charges $1 for every day or part of a day that the item is overdue and the library is not closed for the entire day. 

Actual Results: 

System appears to charge only for full days overdue and may be calculating overdue days by calculating hours overdue, subtracting hours closed, and then dividing by 24.

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