I set non-working days in the configuration panel and we get 2 issues.
first issue: Issues that starts SLA on non-working day are bugged, reseting the SLA after each reload page. I made a test creating another issue on a normal day and everyting did as expected.
Second issue: there are some issues that start SLA one day before an non-working day and the issue bypass, one day after a non-working day the issues are still with SLA in progress but filtering issues with tts.issuesWithRemainingTimeLessThan("1d",24) we got nothing as result, but we have at least 6 issues with the criteria filtered.
I think, whem we set a non-working day, for the plugin, it can't predict a non-work day for JQL methods and it can't handler with and issue that start SLA on a non-working day.