So I implemented that new DO report, which should add a bit more clarity into why the system buys things, not sure if it's greatly useful, so if people have better ideas would be interesting to hear.
The report looks like this (this is my actual PROD positions this morning):
it shows my current actual positions (by particular expiration contract-date), then unrounded ideal positions before DO, then for each case where the ideal is different from actual by more than 1 contract it prints 3 top most correlated instruments with that one.
This should theoretically show me where the missing or extra positions are going to.
So for example V2TX has unrounded-ideal position of -2.62 but actual position of only -1, therefore the report shows me 3 most-correlated with V2TX instruments with correlations: VIX 0.87;JPY 0.63;ZF 0.52, and now I can sort of see that JPY is probably taking risk over from V2TX because it's actually shorter then it's ideal position.
The situation with 3KTB is less clear, it has larger positive position than should, and I could say that some of that extra risk was transferred from GBL(which has +0.14 unrounded but no actual position), but the other 2 top-correlated instruments FLKTB and ZF actually have unopened negative positions, which is opposite to what we'd expect.
Of course smaller correlations from other instruments also affect positions, but this gets complicated and difficult to show I think..