Aircraft models not being produced

[texag11]

Not sure if this is a bug or WAD but playing the Grand Campaign - Additional air HQs and i'm in the last week of May '44 and I have been unable to update to the P-47D-25 or P-51D.

According to the Production screen the first month/year is April '44 for the P-51D and I still have 0 Factories switched over and 38 factories are still producing the B-10 model. The D model isn't even showing up in the Production Screen.

On the P47D-25 it shows there is 47 factories producing that model for the AM side (as opposed to the US which doesn't even show it) and I have 158 in the Pool but they don't show up as an upgrade model.

Rather new so could just be me missing something but based on the dates I assumed I should be producing both.

[Denniss]

US/American aircraft are produced in the USA or Canada. It takes a while to ship them to Europe, just the heavy bombers were able to be flown-in. Thus there's a 3-month delay for smaller aircraft.
Production dates overlap somewhat so you aren't 3 months without aircraft replenishments, just 1 month were you can't use the new aircraft.
Further info: US aircraft may only be used by US units, American aircraft may also be used by certain other nations like France.