This is something that catches my eye.  How many zerocoins are you staking?  There's some debugging options we can turn on to look at what's going on under the hood.

It's known that too many zerocoins takes too long to grind through all the staking calculations, so if you have too many for your system, then you might miss out; by the time you find a winning hash, the next block is already found.  For some systems that number of zerocoins is 1000; I know for my raspberry pi, I see performance impacts when I exceed 200 or so denoms.

There are also some orphan cleanup algorithms that have been improved in the v1.1 release; so I strongly recommend you upgrade [definitely upgrade before the fork on the 31st], and you may find better results.

Feel free to PM me for more discussion; or contact me on our discord.