I believe the developers do not have enough man power to maintain both versions. I am not sure if they are asking for funds because I would most certainly contribute.
I am a “fan” of myIbatis, I use it on my Java projects and used it on the .NET ones. Unfortunately I had to drop it because of the lack of maintenance.
I opted for Dapper (NET) instead, it is not as versatile as iBatis, and you have to include your queries in you Java code, which I am really uncomfortable with, however I have to admit that performance wise Dapper is noticeable superior to iBatis.