Several database-related issues have been found and fixed. Current Qora is stuck with old v1 MapDB due to missing functionality in MapDB v2/3 and the [sole] maintainer of MapDB doesn't back-port fixes to v1 MapDB. Most of these issues are thread-related, like interrupt issues, dangling references for locks, etc. and so mitigations have been written into Qora. Some of the MapDB v3 "fixes" have been manually back-ported into a Qora-unique version of MapDB. Some v1 MapDB issues won't ever get fixed though, like rare race-conditions to do with BTrees.

Hence why Qora v2 uses a different, mature, SQL-based engine with an abstraction layer between that library and the core code making is far easier to replace in the future if similar issues develop.

In relation to Poloniex, I did contact them offering advice, suggestions and my availability for fixing withdrawals. Their last response to me was "I will pass this along to a member of my team and they will reach out if they are interested."