Not possible to set selection based on Action Variable in app

[Lavrans]

I manage to read to datasource based on the same property

Logic agent seems to know this is not possible:

Set Selection-noden filtrerer mot action-variabelen “Beginning of month” via __BUILTIN_ACTION_VARIABLES__DS__. Den datakilden finnes ikke i klientens data-lag når Set Selection evaluerer filteret, derfor undefined.getSingleObject(). Bruk en App Variable med samme dato – eller dropp filteret, siden Read Objects allerede har begrenset Sales (temp).