Make export exclusivity more apparent

I recently had like 20 trucks just sitting there, loaded with dirt, claiming to have "no valid target". This occupied all the trucks, and I had an "extremely busy" status because of this. It took me the whole evening to debug this problem, until I found out that they took their dirt load from a storage that had an export route to a mining tower without a suitable dumping designation.

The problem is that there is no indication that their dirt load is magic and has this invisible destination constraint attached to it.

Please make it more apparent what the problem is than just "no valid target". Draw a line to the source storage. List this constraint in the error description popup. Or better, always list it as the current status of the truck.

My solution to prevent this very issue is usually to assign trucks to the storage, and set it to "assigned trucks only". That way, a completed dumpsite won't tie up 80% of my trucks, it'll only tie up the ones that weren't doing anything else already.

But yes, it can be infuriatingly difficult to tell when loads have special destination constraints, be they dumpsites or even storages, so I absolutely second this.