GPTs no longer referring to Knowledge Source beyond the 3rd/4th message

Hey there, having a new problem with a GPTs I use as a storytelling aide. For context, we basically go back-and-forth, creating new narratives in a well fleshed out world. All details about this world are in 5 Knowledge Source Files. They are formatted, in .txt format, include an index, as well as details about each file within the Custom Instructions (have A/B tested this).

But now it’s no longer checking its Knowledge Source automatically. When it was doing this perfectly before. Essentially, the desired behavior is [User Input containing a particular event/faction/character/etc] → the GPTs looks this information up in its Knowledge Source → and then seamlessly weaves in the details while keeping the overarching narrative in mind.

For example, there is a line:

“Yeah, I had a protege once…”, I let out a deep sigh and look away, “Sneja…”

[the ChatGPT then proceeds to make up facts about Sneja when in fact all pertinent information is given in the knowledge source files]

I have extensively refined and tweaked the Custom Instructions but there seems to be a ‘disconnect’ between the GPTs and its access to its Knowledge Source, unless specfically prompted which just kills immersion.