The filament runout feature has always worked for me but that was with it switching from running out a spool and switching to a new spool or at least one with enough for the print.
I wanted to get rid of 3 or 4 spools, some with less than a meter left so I figured I’d print a reusable spool and play with it. The first spool had maybe a meter on it. When it ran out, I manually followed it with the next color which was also about a meter long. I tried to follow it close enough that it wouldn’t know it had run out. I guess I failed. It triggered a runout sensor somewhere at or after the buffer, paused the print and ran the filament I was hand feeding back out of the 4 way thing in the AMS then ran it all the way back into the extruder and happily picked up where it left off. This color wasn’t even on a spool, just a nice coil with no tangles. When that ran out, it then switched to the spool in slot 2 which has maybe 3 or 4 meters on it.
Some time in the last few days, I mentioned in another post that I thought you didn’t need to load the filament in numerical order for the runout to work, e.g., start in slot one them move to slot two but now I’m not so sure since it started in slot one, ran out then restarted in one rather than moving on to two. Anyhow, it worked and I have 3 less spools of filament that I can’t bring myself to toss! And my reusable spool has 3 colors in 6 layers.