Sorry if this has been posted a million times! I've seen a couple threads about this floating around, but I didn't find a specific solution for it.
The problem: Every API key I make that's associated with my account is rejected by all 3rd party tools (GW2Efficiency, Discord Bot, Discretize Website, Snowcrows Website). I've messaged the dev for GW2Efficiency, and they said that the error returned is "ErrBadData". I've also contacted support, but they said they couldn't help beyond creating the API keys themselves. I've waited roughly 2.5 weeks now to see if maybe it'd be patched, but I'm still getting the error despite making/deleting keys every couple of days.
It looks like people have managed to fix this (or have it be fixed for them) in the past:
https://en-forum.guildwars2.com/discussion/20110/my-api-key-is-broken (note: this didn't work for me)
Thanks in advance for any help!