Large number of unassigned cells with threshold equal to 0.5

[fbrundu]

I have a dataset which I want to annotate, however most part of the cells (89%) end up unassigned even setting a low threshold (0.5). How can I troubleshoot the problem?

The training dataset is defined here: https://cells.ucsc.edu/?ds=cortex-dev
The testing dataset is composed by 6 unaligned batches, for a total of 30k cells, and sequenced with 10X.