Hmm, ok. I added a single line of belt bevor the splitters and now they work as expected. So Inserters in Splitters behave different then "inserts" from belts?

On your comment: So this is not a bug but a feature? I don't mean the splitting, just that it does not continue if not inserted by belts ...

I reworked my train stations to have 6 stack inserters with steel chests behind them, another row of this combination finishing with 6 Splitters in a upside down pyramid to reduce the numbers of belts. this work for 4 of 6 chests but the outer chests (to the left and right) are not emptied, as the ...