Here is the Cryptopia response to me, regarding BCN. Maybe I misunderstood. Please advise if it makes any sense. If not, I can ask for clarification. It's a bit raw. It seems to be important to me, if it can cause problems for XMR's (and Aeon) down the road.
"You've basically got the right idea. Polo sends about 90% of their cryptonote transactions to us just fine, but they encrypt the payment IDs of the other 10% with some password we've not yet figured out. We tried to contact their support to explain what they were doing but much like their users, we've been waiting for months with no reply. We have a working theory that like us, Polo has issues with Cryptonote wallets timing out calls, and thus it's probably only the manually reprocessed transactions that are going badly - when you google it, in many examples of how to send transactions for Cryptonote, the user is instructed to use a password to encrypt the paymentid - we assume that whoever is redoing their transactions doesn't know what they're doing.
"There is 2 major problems with this for us. The first being that many smarter users starting watching the blockchain for encrypted payment IDs arriving at our addresses, multiple users would then log support tickets claiming that the transaction was theirs and that they should be credited. A single transaction with an encrypted paymentid doesn't create a single support ticket, it creates many.
And so we just sent all the encrypted transactions back to Polo, we even paid the fees to do that, with the same encrypted payloadid hoping that Polo would figure out what we were doing and why, but, alas, nope. We then started getting user complaints that people were trying to move funds from Polo to Cryptopia, and that we were essentially rejecting their money and sending them to Polo's support to wait 3 months for shits and giggles.
"On one hand we get called thieves, and on the other we have users trying to leave Polo to come to us and having a very nasty first user experience which is out of our control. Either way, the support overhead makes us run at a massive loss to support Cryptonote coins, and the negative reputation we get for Polo's mistake made it a pretty clear cut "sorry, but this is why we can't have nice things", and is the reason that we don't accept new Cryptonote coins and are actively delisting the ones we do have. It's nothing to do with any KYC/AML requirements; it's nothing to do with the anonymity components of the coins/protocol; it's simply a bullshit sandwich being served up by Polo that we don't wanna eat anymore.
Worth noting is that for whatever reason, this issue doesn't happen nearly as much with XMR (like 0.5% of the transactions vs 10%), I dunno why."
Polo is too big and fat to react quickly and smoothly
