Custom instructions and GPT actions

To manage the actions of my GPT, I have followed what seems to be a common approach:

  • I paced a series of “hot key → action” relations (in a txt fileuploaded to the knowledge files) which are displayed upon pressing a menu button.
  • I specified (in the custom instructions) what action to perform when a hot-key is prompted.

For example, if the user presses the menu button, it is shown:

BM-US → US bond market data
BM-UK → UK bond market data

Then if the users prompts BM-US, the custom instructions tell the GPT to retrieve the US bond market data.

This has been working on and off forever. However, since GPT-4o the GPT is completely ignoring the custom instructions that say what action to perform when a hot-key is prompted.

How have other GPT creators solved this? Does your setup differ?