it could be - a cognitive distortion. AND it could be that in flashbacks something else needs to be in place first. I am uncertain. I have dealt with flashbacks - and come through. And now group therapy is DBT oriented. Today, in fact, he was talking about suffering and how we make ourselves suffer more than we need to. Now had i heard this while i was in flashback mode, i probably would have told him to stuff it. He hasn't ever had a flashback so I don't feel he'd really know.
That said... I can kinda see where he is coming from (now that I am several years without the terrible cycles of flashbacks).
I am trying to remember what helped me with those... I don't think it was anything my Ts did. I found tangeable things to be useful - lavender oil to cut through the past with its sharp scent, and then calming after-scent. A stuffy or stone to hold on to. Repeating my name, current age, current residence, current phone number, and saying "I can be safe". Not "i am safe" because clearly in that moment the mind does not feel safe and lies are not helpful. There is also a pressure point between the last 2 fingers that you can lightly squeeze that helps with the anxiety. Deep breathing to calm the heart also calms the mind.
Personally, i think that when in a flashback, the mind is trying to get OUT of the body, so mindfulness about being IN the body and aware of surroundings (when the mind believes the surounding to be dangerous) is counter-intuitive.
Perhaps mindfulness can be useful once the flashback has ended as a self-soothing technique.
Also, for me body mindfulness creates panic and flashbacks because I spent so much time out of my body, since the body was "dangerous". But that is just me and my current work.
Anyway, feel free to ask questions or PM me anytime. Hope things get better for you!!!