I can see the problem. However, and speaking as a non-expert, -ve correlation of returns to me does not necessarily mean -ve correlation of momentum. GAT is the expert so I shall wait to hear if has a view on this.
No expert, but this is the way I see it. The following should be obvious:
Negative correlation is GREAT if you're running a long only strategy, especially if leveraged eg risk parity (Because... diversification.)
Positive correlation is GREAT if you're running a spread or cointegration strategy.
Near zero correlation is GREAT if you're running any kind of long/short timing strategy, which includes momentum plus carry (again diversification)
High positive or high negative correlation is BAD If you're running any kind of long/short timing strategy, which includes momentum and to a lesser extent carry.
Momentum cares about ABS(correlation) rather than Sign(correlation)
We can't do much about the correlation, but if reasonably predictable can try and run strategies that suit it. It looks like the correlation between bonds and stocks is going from being pretty negative (great for risk parity, bad for trend following) to being close to zero or even positive. As long as the correlation isn't too high this will probably be a better environment for trend following, in as much as it will offer better diversification.
Generally the correlation of a long/short timing strategy will be closer to zero than for the underlying assets, because slight differences in the price series will result in slightly different positions, and hence relatively large differences in return streams.
GAT