As you can see there are plenty boarding desks jobs which are not claimed yet, but they don’t appear in the column “jobs available” (unless janitors are supposed to do the boarding).
Employees do not try to claim jobs they’ve once failed with and before they consider a job failed they try multiple times. Do you have any pathing issues or other problems with employees or passengers reaching that area?
Not sure, would need a lot more information to debug the situation. We do not currently have any widespread issues with employees not doing their jobs so there’s either a design issue that’s not obvious enough or a very specific bug.