Had a situation where at 99% on stage 4, the scythe head of Lephantis refused to open; he just kept ground pounding. Luckily I had a Glaive prime, and just randomly tried the heavy throw explosion, and every few times it somehow did damage. I used this to finish the bounty without needing to abort. If this doesnt get fixed, maybe glaives can be a work-around. I think someone in my group used a slowing ability (don't know which) on him, and we had a Wisp Prime with full motes active, not sure if this contributed to the glitch or not. PS5 user.