'branch_mutations.txt' output always empty (v 0.11.3)

[LewisCEMason]

Dear Devs,

I hope that you are well.

I am using TreeTime (v 0.11.3), installed with conda install bioconda::treetime.

I am using the ancestral sequence reconstruction (with VCF files) command, treetime ancestral --aln data/tb/lee_2015.vcf.gz --vcf-reference data/tb/tb_ref.fasta --tree data/tb/lee_2015.nwk , (but with my own files) as a means to obtain the branch_mutations.txt output, but am finding that this output is always empty. The other outputs (ancestral_sequences.vcf, annotated_tree.nexus, auspice_tree.json, sequence_evolution_model.txt) are not empty.

I am unsure of what is going on here, and was wondering if you could help?