I have a train setup that isn't completely filling despite the fact that it should be able to do so. It is the "Crude One" line in the attached save. Note that it always only loads the train car that is at the loading platform for the resource, it doesn't progressively load all available cars with the resource. There is only one loading platform of the "fluid" type. The other two platforms are unload only, but also fluid platforms.
I think in the current version of the line I have a timeout on the fill, but even with it removed the same issue occurs.
save.save
Files not imported: save.save