bitgrail
explanation for newbies: Raiblocks is a pow coin (proof of work, google is your friend), so every transaction that the bitgrail's wallet receive/send make the server's cpu working at 100%, when bitgrail has a day like this, with a loooot of transactions, some delays may come up...
Today it was worst than this: today the wall Raiblockschain got reaaaaaaaally slow due to the huge increase of transactions to process.
What happened when this happens? Invalid blocks. Invalid blocks are like not-yet-born children: they are there, but not yet fully built. The same for those blocks. (Don't worry you didn't lose money).
From our side, the rai_node was super duper overloaded of deposits and withdrawals. That means that if usually it takes 1/15 minutes, now it may take up to 24 hours due to the pending transactions (see about the pow).
Even though this process is automated, the chain and the node needs time.
The only thing to do is to wait
Shouldn't the transactions be instant though? That's literally the only selling point of this coin.
Don't forget about almost unlimited divisibility and transactions without fees.
RaiWalletBot: 10-20 seconds between send-receive and several thousands transactions/hour without problems. For large services it depends on implementation and computing power for peaks.
I guess many services doesn't want to upgrade servers etc. so perhaps some distributed PoW with fees can be an future option for them.