Hyperparameter_search does not log params after first trial

I am using Trainer.hyperparameter_search with the optuna backend in transformers 3.5.1. When I run a search, the model params (./mlruns/0/<ID>/params/) are only logged for the first trial but none of the trials after that. The model metrics are logged normally in ./mlruns/0/<ID>/metrics/ for all trials.

Is there a way to get the params to be logged? I’d like to automate some analysis and visualization and it would help to have those param values available in the ./mlruns/0/<ID>/ directory.