Currently the Loaders only support a belt stack capacity of 5. can you make them work with higher stack sizes?

They will work with whatever the maximum stack size the belts will support. Factorio will only display 4 layers on the belt graphically, but there are actually more there.

i did not test the new 1.0 version yet, but when i reported the issue it was "hard capped" at 5 stack size 100% i did multible tests, and tested only with your mod and a mod that incressed the stack limit on belts and it was not only visualy. the "stacksize" slider was maxed at 5 while other loaders were able to output higher with research. i switched to a mod that changes loaders on the prototype level called "Stacking Loaders" and disableing the stack loaders from your mod. that fixed the issue back then.

Which mod did you use then? Are you still able to reproduce the issue? Perhaps provide a save file with the issue?

as i said i used "Stacking Loaders" by protocol_1903, ill try to reproduce the issue and report back

im not able to reproduce this with version 2.0.61 of Factorio, newest version of LM and Beltstacking mod by notnotmelon