I tried to use 5.4 for something pretty straightforward - create scripts to automate navigating a game UI and capturing the network traffic. 5.4 was super frustrating, constantly stopping and waiting for feedback etc, even after telling it to never wait and just iterate/debug. I quit and switched to Opus 4.6 and it did much more of the work by itself.
I've never run into that problem, but these were coding solutions in codex with a strong plan, steps to work towards.
It could be that if you're using massive tokens on a 'plan' then then want to limit u in a way, or even if the objective is not perfectly clear they don't want semi-random token use.
See if the token/sub solution behaves differently. Make sure that when it 'compacts' that it re-reads your instructions clearly.
Well I wish I could help - but things changes so fast - codex with opus 4.7 is not very strong. you have to set the effort level relatively high though.
