Files inaccessible by assistant api in api mode, but accessible in playground

so, i am using the openai assistants api in my app. We are doing some RAG type stuff. issue is, the file is not accessible to assistant and its code interpreter fails to access the files and give results.

the same assistant, if used in openai playground, can easily access the file and create results. can you folks help me with this issue?

this is a quite persistent issue i have been seeing from few months at this point now.
the assistant is the same one used for both the tests and it was created using API and not through playground.