Hi William,
When configuring an SLA, you can configure the time to be calculated as business or calendar hours. In both cases, the actual 'deadline' will be calculated, but the countdown towards this deadline will be displayed in absolute time. This absolute time will then be recalculated to days, hours and minutes to provide a more readable result.
As such, when selecting business hours, the absolute time until the deadline will only calculate for the number of business hours set in Configuration\General Settings\Business hours and thus this deadline, recalculated to days, will show and higher value as expected
More information on setting SLA's can be found in the below article.
https://www.lansweeper.com/knowledgebase/configuring-service-level-agreements/