True Cockpit mode is mainly for the VR, it is an ongoing implementation - once it’s finished it will have the description and we’ll get more feedback on it from Asobo.
The loss of the free view camera mode in the cockpit and external views is not related to the True Cockpit mode - you need to check out your settings under General–>Camera to see what is set as the preferred way for the freelook mode between the Toggle/Hold - then check the Mouse assignment for the Toggle freelook (Hold), etc.
There is a particular way of how it is set to work, just carefully go trough those settings, read the descriptions and you’ll figure it out.