@cookoo
Thanks for the comments.
Yes, when I am removing the dashcam, I am pressing down the lock button to lift up the latch in the tube and to 'unlock' the body
With body removed, I can see the latch moving up and down in the tube when I press and depress the lock button.
However, there is no need to push hard and keeping lock buton pressed when inserting the body back. It just slides in easily and 'locks' in its place. There is obviously no space left to move any forward
I have tried inserting it, however, with lock button pressed (as you have advised) - this makes no difference. Body locks when I depress the button, can't be removed, rotates with clicks.
But, it is still loose in the mount ring anyway, maybe latch is not releasing completely or there is a problem with a latch spring.
Anyway, I have contacted the distributor already and they have advised that they would provide a replacement mount bracket for me.
Meanwhile, just to re-confirm - dear owners of Blackvue dashcams (with the ring front mount) -
could you please confirm that once your dashcam is clicked-in the mount - it is siting tight and does not stagger in the mount when you try to sway/shake it with a hand?