Not sure what’s going on here, but I think it’s something to do with whatever voodoo is used for dealing with multiple production facilities on the same line.
I’m getting a next slot not found, even though it’s definitely there as per the first screenshot. The way to fix it was to remove the conveyor section where the lines from the two paint slots meet, as per the second screenshot. As soon as I added that square back in everything started working again as shown in the third screenshot. The appropriate save file is attached, and the bug should appear as soon as you open it.
On a related note I did get something similar with a resource conveyor saying that it wasn’t connected, however a re-load of the save fixed this and I can’t replicate it any more.
Matt.xml (192 KB)