I wonder if you're talking about me and my 5 catheter journals. (which I actually wrote over 7 months of using catheters). The answer later ended up being that I did have Detrusor Sphincter Dyssynergia (and probably Bladder Neck Dyssynergia too). Both were in the early stages so it was not fully apparent at that time. My external sphincter was always, and automatically, clamping down (lightly at first, but as hard as it could later on). I had to strain to pee, so I instead used catheters for 7 straight months in an attempt to make me fully open and incontinent. I did this until it hurt and I couldn't use them any more, which is why I stopped at seven months.
Most normal functioning people would have been relaxing their sphincters that entire time, unfortunately for me, mine was still clamping down the entire time so I quickly went back to my precatheter state afterwards.
FYI, I have since also had SIX urinary sphincterotomies, and likely need one or two more. This has been necessary for me in order to lessen my off-the-scale internal bladder pressure which had caused rectal problems and bleeding, and was showing signs of causing renal problems too. I'm probably 80% recovered from that now, but have a little more ways to go.