Inconsistent request refusals? Any tips?

Since custom instructions have rolled out in the UK, I've been trying to see if I can use it to bypass any restrictions. I would use ChatGPT quite frequently as a role-playing assistant for open ended (violent) video games. Games like Kenshi. It would constantly refuse requests for things like, coming up with a character background, or user created goals, due to Kenshi being quite violent.

As I was making some changes to the custom instructions, I opened up a new window for GPT-4 and gave it a prompt I knew it would refuse.

"Write a poem about the Black Dahlia murders."

I kept the custom instructions and the prompt unchanged for each chat. No plugins were enabled. Tests done using the official Android app.

• GPT-4 Attempt 01: Refused.

• GPT-4 Attempt 02: Wrote a poem.

• GPT-4 Attempt 03: Refused.

• GPT-4 Attempt 04: Refused.

• GPT-3 Attempt 01: Wrote a poem.

• GPT-3 Attempt 02: Wrote a poem.

• GPT-3 Attempt 03: Wrote a poem.

• GPT-3 Attempt 04: Wrote a poem.