Variable sort order wrong

I get this issue :
When I declare a variable (i.e. : year and month lists) then ask for descending order (either numerical or alphabetical : same issue) then go on an other dashboard and then come back in the dashboard vith the variables I get an ascending order instead of a descending order while in the variable preview values the order is good. Same issue if I ask refresh on dashboard load.
Could you let me know how to get the good descending sort order (grafana 5.4.3) ?