What are you using that’s different than standard Roblox procedures? Since it isn’t what normally happens in Roblox I’d look at what changes you’ve made in your game and assume that the issue is there first.
Your character movement seems different so I’d suggest looking there first.
Another day another Humanoid problem. It’s all to do with HipHeight in this scenario you doing anything funky and different from expected Roblox procedures like @Scottifly said like changing the collision groups? Welding to the character humanoid root part? Using a custom character rig with a humanoid hip height set to zero?