Ok, I found this online, I think sadly, it answers my question.
Some ICAO codes might not appear in Jeppesen because the data provider chooses to only include airports that are considered significant for commercial aviation, meaning very small or remote airstrips with ICAO codes might not be listed in Jeppesen due to their limited operational relevance for most pilots, even though they technically exist in the ICAO database.
Key points to consider:
- Data selection:
Jeppesen curates its data based on factors like traffic volume, aircraft type compatibility, and regulatory requirements, so not every airport with an ICAO code will be included.
- Regional focus:
Depending on the region a pilot operates in, Jeppesen might prioritize listing airports relevant to that area, excluding less important ICAO codes from other parts of the world.
- Access level:
Certain Jeppesen subscriptions might have access to a wider range of airports with ICAO codes compared to basic packages, meaning some airports may only be visible with a higher level of access.
In other words, if you like to fly to smaller airfields, a Navigraph subscription isn’t going to do much for you and you’re better off just using MS/Asobo’s crappy flight planning tools. Bummer.