5.6 Terra High has become stupid and consumes all tokens on simple tasks

What issue are you seeing?

5.6 Terra High has become stupid and consumes all tokens on simple tasks.

Having used the 5.6 Terra model at length doing similar tasks, I've noticed an enormous change in its behaviour very recently.
It now churns through tokens like they're made of air and gets nowhere.

Just now I tasked it to compile 15 sentences into a docx. following a protocol it has followed all month with no problems.
It didn't follow the protocol, made up its own, erroneously printed each on a separate page instead of all on one page / with non-wasted space.

On pointing out its failure and requesting it sticks to ordinary workflow, it acknowledged and then proceeded to use 5% (from 9% to 4%) of 5h usage and created a newly exported version with two per page. still completely incorrect on a simple task of pagination.
On reiterating the simple task, it consumed the remaining 4% of 5h usage and ceased working.

What steps can reproduce the bug?

Request any simple task be done using Terra 5.6 on Codex Desktop for Mac

What is the expected behavior?

Continuing to follow simple instructions, and not burn tokens doing nothing.

Additional information

No response

Start by reproducing the issue in Codex Desktop for Mac with the Terra 5.6 model using a simple task that follows the reported protocol. Done means the task follows the instructions, produces the expected pagination, and does not consume excessive tokens.