The documentation of /me/associated says:

You can filter the network_users returned by this method with the types parameter. Specify, semicolon delimited, main_site or meta_site to filter by site.

However, using the value meta_site doesn't give any items (even though, for me, the total is shown as being 175, which is correct):

{
  "items": [],
  "has_more": false,
  "quota_max": 10000,
  "quota_remaining": 9993,
  "total": 175
}

Not using the types parameter gives a total of 177, which is indeed the number of main sites I have an account on (Meta Stack Exchange and Stack Apps don't have a Meta site, that's why this is 2 higher.) Using the value main_site also gives a total of 177. Here, the items (site accounts) are returned as expected.

This issue is perhaps related to Meta sites in “Your Communities” display different reputation.