This plant is completely ignored by Bristle-noses in my tank, I have several adults, very capable of chumping bogwood so if you have some they may possibly be the guilty culprits, but I doubt it. I only have a few Amano Shrimp so hard to provide a defence for the crustaceans but seems a bit severe for shrimp damage.
I personally would suspect drastic melt from flow from a cleaned out filter, or water chemistry issues, or CO2 deficiency or some nutrient deficiency, something drastic to quickly and comprehensively damage the plant, and then the shrimps are simply munching on the weakened easy to digest leaves.
I find these false lilies easily damaged by current and cold water. Any Oscars in the tank? Only joking.
Bad luck all the same.
Trim off at the substrate, pop a nutrient tab in, and with strong light and CO2 they should quickly regrow, it is actually a nuisance plant in my four foot. But I find it Iron hungry or the leaves weaken round the perimeters. Sorry I can't be more helpful.
