The next issue is with this statement.
from openinference.instrumentation.openai import OpenAIInstrumentor
OpenAIInstrumentor().instrument(tracer_provider=tracer_provider)
you need to set the tracer_provider variable when you register the provider.
from phoenix.otel import register
# defaults to endpoint="http://localhost:4317"
tracer_provider = register(
project_name="my-llm-app", # Default is 'default'
endpoint="http://localhost:4317", # Sends traces using gRPC
)