MiXCR failing to extract VDJ from B cell fastq.gz

I am trying to extract BCR data from single (B) cell RNA sequencing data (SmartSeq, Nextera, HiSeq4000) to compare clonotypes between two samples. I’m particularly interested in comparing % germline mutation to look at affinity maturation.

These are the settings I have used:

I have tried running one of my samples (= 81 paired reads, i.e. 81 B cells) with MiXCR with the shotgun analyze approach for non-enriched libraries, and it seems to run without any errors but all the clonotype tables are empty.

The report for the same sample shows this in the final section which makes it look like contigs have been generated. Could you please advise how to get these to export?