i have been on the mac version since 1.1.5 and this function has never worked. no matter what length i set that to it will still print microscopic sized infill bouncing the extruder all over making little dots of infill. this isnt a huge issue for me obviously since i havent ever reported it in the 10 mos or so i have been using s3d but it really should be fixed at some point. either that or i'm completely not understanding the function of this setting.
Are you sure you're using the latest software? I just tried a whole bunch of different thing with 3.1.0 and the min infill length setting is working perfectly fine for everything I tried.
- I tried adjusting the setting to make sure it actually stopped small infill regions from being printed in some of my models - that worked correctly
- I tried creating a profile with a special min infill length setting and going to File > Export FFF Profile - that worked correctly and it had the right value in the file
- I tried saving and switching between different processes that add had different min infill length settings - those all worked correctly as well
So if you want help, perhaps you need to attach some sample files and explain the exact steps you are taking.