I would argue that the CB-4684 : Investors are not appearing within an InvestorInvestment is still not fixed.
The funding round has an Investment relationship, which consist of the Investor items. As you can see, the only relationship with an Investment is funding rounds (open the url above with your user_key or look at the json below).
"relationships": {
"investments": {
"cardinality": "OneToMany",
"paging": {
"total_items": 1,
"first_page_url": "https://api.crunchbase.com/v/3/funding-rounds/a217ca4f22b388b5d78fae7673b3d4a0/investments",
"sort_order": "created_at DESC"
},
"items": [
{
"type": "Investment",
"uuid": "e40708f86713217833fd16365e89bc3a",
"properties": {
"money_invested": null,
"money_invested_currency_code": "USD",
"money_invested_usd": null,
"created_at": 1379943313,
"updated_at": 1412124958
},
"relationships": {
"funding_round": {
"type": "FundingRound",
"uuid": "a217ca4f22b388b5d78fae7673b3d4a0",
"properties": {
"permalink": "a217ca4f22b388b5d78fae7673b3d4a0",
"api_path": "funding-rounds/a217ca4f22b388b5d78fae7673b3d4a0",
"web_path": "funding-round/a217ca4f22b388b5d78fae7673b3d4a0",
"funding_type": "private_equity",
"series": null,
"series_qualifier": null,
"announced_on": "2013-09-23",
"announced_on_trust_code": 7,
"closed_on": null,
"closed_on_trust_code": null,
"money_raised": 5000000,
"money_raised_currency_code": "EUR",
"money_raised_usd": 6433000,
"target_money_raised": null,
"target_money_raised_currency_code": null,
"target_money_raised_usd": null,
"created_at": 1379943313,
"updated_at": 1398009899
},
"relationships": {
"funded_organization": {
"type": "Organization",
"uuid": "d7a950bbbbd9bbbf77ac4235c707cb68",
"properties": {
"permalink": "dns-net",
"api_path": "organizations/dns-net",
"web_path": "organization/dns-net",
"name": "DNS:Net",
"also_known_as": null,
"short_description": "DNS:Net provides telecommunication, internet and data-center services that target private and business customers.",
"description": "Established in 1998, DNS:Net provides telecommunications, internet and data-centre services, targeting both private and business customers. The company has more recently diversified its offering by providing broadband connections in the Berlin area.",
"primary_role": "company",
"role_company": true,
"role_investor": null,
"role_group": null,
"role_school": null,
"founded_on": "1998-01-01",
"founded_on_trust_code": 4,
"is_closed": false,
"closed_on": null,
"closed_on_trust_code": 0,
"num_employees_min": null,
"num_employees_max": null,
"stock_exchange": null,
"stock_symbol": null,
"total_funding_usd": 6433000,
"number_of_investments": 0,
"homepage_url": "http://www.dns-net.de",
"created_at": 1379943112,
"updated_at": 1432074249
}
}
}
}
}
}
]
}