As for Karabakh Armenians supposedly “not trusting Azerbaijan’s assurances”, it’s less about that and more about their hate of “Turks” (Azerbaijanis). They can’t ever imagine themselves of accepting Azerbaijani jurisdiction, as they are (supposedly) “a superior race and people”. So they made their choice, rather than accepting Azerbaijani jurisdiction, they left.
This 2016 music video filmed in Karabakh boasts about how “World was shattered by the Armenian fear, Turk’s throne fell to the ground”.