Can you upload screenshots and/or a video of what you’re doing?
I had a similar issue with a train system that I was creating (station platform logic), but I’m not sure how similar my case and solution is to yours.
Just keep in mind that NavMeshes are really not meant to be dynamic. They can be, but when they are, they’re very inflexible. This is for stability, performance, and consistency.
I’ve found that the dynamic NayMesh is not really for movement, but for actors that come in and out of existence (i.e. loading/unloading levels/zones); that way your character doesn’t avoid bumping into phantom objects or fall through floors that no longer exist.