Bug: --config.learning.finetune_backbones=True

Hi,
When I add --config.learning.finetune_backbones=True I get the following failure.
ValueError: Unknown signature default in checkpoints/imagenetr50/ (available signatures: _SignatureMap({'representation': })).

I am trying to just run the finetuning baseline to reproduce some of the results in the paper but cannot get past this error. I was wondering what kind of setup you had to run this experiment since it seems like TF1 Hub does not support trainable=True parameter for some models and it seems like this may be one of them.

I tried pip install --upgrade tf-hub-nightly but still get the error.

Thank you!