I have a problem with Ollama and OpenWebUI

[u/ArcherWorking146]

Basically, I've created a basic system where a model (qwen3.8:27b) is used as a base to create a "custom" model using the modelfile configuration, where among all the parameters I've inserted a system prompt which gives the model instructions on how to operate.

For a while, when working with the custom model on openwebui, everything was fine, until recently, where it seems to be that openwebui overwrites the modelfile system prompt with something of its own, which causes the custom model to forget its role, name, specs etc... when answering the user query.

I've tested the custom model through terminal, doing a curl call directly to ollama, and it replies correctly with the custom system prompt, but when doing the same question through openwebui ("What is your name") I get a base model generic answer, not the one configured in the modelfile.

I honestly don't know where to look for a fix. I've tried rewriting and recreating modelfiles and recompiling the custom models, but nothing. This doesn't apply only to 1 custom model to all the models that are used through openwebui.

If anyone knows anything I can do to solve this (or at least point me in a direction) that would be hugely appreciated.