Ann: Quarterly Activities Report, page-4

I think there are a few possible reasons why the sp has drifted lower since the change of strategy;
The longer wait for the DFS has pushed out holders with a shorter time frame
The potential uncertainty created by the change may have led to some selling
Selling leads to more selling until it gets overdone and a reversal higher kicks in again.

As for the uncertainty created by the change of strategy, the CEO Lindsay said in the interview that fertiliser prices are up and it has helped MNB.
In the interview Lindsay referred to the 31-33% phosphate rock price being at least $300 landed in Angola.
I've also heard that pricing would be determined by relative agronomic effectiveness, meaning prices could be much higher. Lindsay also mentioned the "secret herbs and spices" which might be a reference to a way of making the PR more soluble again increasing its performance and potential price.
I ran some spreadsheet numbers to compare scoping study numbers to what would result from the new product phosphate sales if it sold at US$300/t (same price as 31-33% PR).
I compared that to enhanced product pricing that was the basis of the scoping study, at a couple of MAP prices up to the $643 (2nd column) which was the maximum assumed in the scoping study. With MAP at $643, EPR would have sold for $350/t but cash cost would have risen to $173/t with the higher MAP price.

It looks to me that the new product will be more profitable (third column) thanks to the current high phosphate prices and the lower cash cost for that product with no MAP input. Hence the change of strategy. If prices fall sufficiently to make the EPR more profitable again, the company has the option to switch back.

I also ran numbers at the starting plant capacity of 150ktpa, as well as the two stages of expansion up to 450ktpa as in the scoping study. Results below show much higher profits now than anything assumed in the scoping study. The project is worth much more now than at any scoping study assumed prices.

Even after just the first expansion to 300ktp, annual cash profit would exceed the current market cap. It amazes me how much value there is in this stock. - Then there's the green ammonia!