I ran into the same binary files problem. In my case Codex had actually added one binary file (png file, probably it made a copy of my existing file for some reason). Noticed that when reviewed the list of files and diffs.
I asked Codex to remove that file as it should not have been added in the first place. After this it was able to create the pull request.
I sometimes have similar issues, but I do not see you describe it as exactly the same.
The issues I used to get often:
It will say ‘‘update branch’’ in the top right instead of ''create pull request".
Or it will just say create pull request, but when you do it seems to use a old PR.
To avoid these kinds of conflicts I have changed my way of working:
For each issue/update/feature I write using codex I start a new task. After having made 1 PR I make a new one. And I archive the old ones. That way you can also find old PR’s back easy if need be inside codex. Although I do not really see a practical use for that.
For the “Binary files are not supported”, another option that worked for me is to:
use the “copy git apply” (under the menu of create PR)
patch this locally
push it your self to a branch
I also point this out in my video on YouTube " Use Codex by OpenAI to Build a .NET + PostgreSQL App in 5 Steps + fix Binary files are not supported" (at 4:23)