Block 3 is probably not as incremental as we are led to believe. Here is why I think so:
1. JF-17 was initially a stable design. Block III is likely to be an unstable design (like the F-16). This means thre will be basically a completely new FCS.
2. AESA radar is likely to be immature and attempting to combine air cooling, solid state cooling and liquid cooling. Far more than the technical aspect, it is ironing out the endless coding that will be difficult
3. Same as point 2 but related to sensor fusion and EW - a lot of coding can go wrong.
However, I do believe the Block III will be on time and we will all be surprised with perhaps 24/25 new aircraft in Late October / November.
@airomerix said that people aren't allowed to go in the production area due to COVID 19, meaning workers are working there, meaning production is taking place. JF-17s (and all modern aircraft) are built in batches, meaning if they are building 1, they are likely building a whole batch. Last known batch capacity is 24/25.
JF-17s are supposed to take a year to get produced in that number. We know production started in November, meaning by October this year, batch is supposed to be complete.
Where are you getting information about the design?
And viola, there we have it. Simple logic and reason gives us the right Occam's razor result.