New category is None

[ZitengXue]

Hi! authors, thanks for your great job! I tried to train the code with the order:
bash configs/COCO/R50_dab_ovd_3enc_apm128_splcls0.2_relabel_noinit.sh RN50 2 local and set batch size = 2
When running to the second iteration, the new_category in Classifier (line 131) is None and the training is stoped. How can I fix it?