I have a setup where a purifier is next to an assembly machine with the refill filter recipe, so that when a filter is used up, I can automatically refill it and go back to purifying. This works most of the time, however, I keep noticing that on occasion my filters will just vanish. No Air Filter, no Used Filter. This appears to happen at about every 5-10 times my purifier finishes with a filter.
I'm not sure if this is intended behavior or a bug, since the tooltip doesn't mention anything about % chance to lose the filter. I am running Krastorio 1.4.36 with a couple mods: alien biomes and auto-deconstruct, but the purifier isn't being deconstructed or anything. It just runs out of reagents because all my filters vanish.