I have created an app where I use a data source(Excel table,Ondrive for Business) I use a specific LookUp against this data source multiple places in the app, to manipulate colors, checkboxes and more.
When I were revisiting the app to do some changes, and noticed that all the checkboxes were checked off all colors where set to "Marked" in the dev environment.
Published the app again(now powerapps version 3.18081.19), all checkboxes is checked.
After the checkboxes where unresponsive I emptied the data source. All checkboxes still marked off.
When I rollback, the formula still works (powerapps version 3.18063.33, Euro style code)
!IsBlank(LookUp(EmployeeData;Emp_name=User().FullName And Emp_certification=Gallery1.Selected.Titles))