Anubias Nana - Keeps dying?

Can you define dying? Are the leaves turning yellow and then fading away, or is something else going on?

How far away from the surface of the water are the plants located, and does your water test just fine (do you have fish in there, shrimp, or any other sort of livestock)?

Do you have a lot of light shining on the plant? This can be what causes it to die if you do. The anubias nana plant likes to grow in the shade so that could be one cause.

Hope you get to the bottom of what is happening.

Ah, mate, sounds like you've got a bit of an Anubias nana mystery on your hands! It's a bummer when your plants keep kicking the bucket, ain't it? Anyways, let's try to figure this out: make sure your water's all good and dandy, check those light levels 'cause these plants like a bit of shade, and maybe keep an eye out for any hitchhikers in the tank that might be causing trouble. Hopefully, we can crack this case and save your green pals from their untimely demise!