The back of the tile and back of the schlueter edge should be 100% filled with thinset, so there is no way you should be able to tape behind it.
If you are saying there is just a small gap there, I would fill the gap and edge with durabond and then embed Fibafuse tape in it, wiping that down tight. The tape does not need to go behind (dont see how that's possible) but if it does that's fine. No do not get your tape on the edge. Then apply your regular joint compound over that, keeping the edge clean.
Dont know what kind if finish your edge has, but sanding the drywall could damage the finish, so you might just want to scrape and use a wet sponge tgere as much as possible rather than sanding.
If you are saying there is just a small gap there, I would fill the gap and edge with durabond and then embed Fibafuse tape in it, wiping that down tight. The tape does not need to go behind (dont see how that's possible) but if it does that's fine. No do not get your tape on the edge. Then apply your regular joint compound over that, keeping the edge clean.
Dont know what kind if finish your edge has, but sanding the drywall could damage the finish, so you might just want to scrape and use a wet sponge tgere as much as possible rather than sanding.
