The agent who interviewed LTG Flynn was none other than Peter Strzok.
It all depends on his word against Flynn’s, about who said what, in a meeting between them.
Strzok probably just lied about what was said, to set up Flynn.
Strzok’s texts rebut the presumption [I know, but the law is a ass that is what the law presumes] that he is an honest, reliable and neutral public servant. Therefore his testimony as to what Flynn told him is not reliable evidence and that fact is material to Flynn’s decision to accept a plea. I am sure that there is a lot more than that, but that is the start of the legal argument. Then, that his boss McCabe wanted to eff Flynn so that they could eff Trump creates the presumption of a conspiracy to deprive Flynn of his civil rights etc.
*** “Strzok probably just lied about what was said, to set up Flynn” ***
There is the Rub ... It is LEGAL for Strzok to LIE
No doubt with encouragement from Mueller or his goon Andrew Weissman.
At the time the Flynn controversy erupted, the word was that Flynn was "cooperative and truthful" in his FBI interview. But of course Mueller hadn't yet been appointed and didn't yet know how scarce defendants would prove to be.