Compared to calling version 2 of the API with a large page size, the list of sites in v1 is getting truncated after Salesforce Meta.
From the API 1.1 docs:
The V1.x family of APIs is obsolete, having been replaced by the V2.x family.
New applications should use V2.1, and existing applications should migrate to V2.1 as well.
Existing API V1.x endpoints are still supported, but we are no longer creating new ones for new Stack Exchange sites. (emphasis mine)
Presumably, Salesforce was the last Stack Exchange site created when API 1.0/1.1 was still active, but newer sites are not getting their API endpoints created.
The original announcement on StackApps regarding the deprecation of API 1.x can be found here. (Oddly enough, it looks like Libraries was supposed to be the last site created with an API 1.0 endpoint, but the deadline was apparently extended).