This is WhatsHap 2.8 running under Python 3.9.23
[E::idx_find_and_load] Could not retrieve index file for 'input_filtered.vcf.gz'
[E::idx_find_and_load] Could not retrieve index file for 'input_filtered.vcf.gz'
[E::idx_find_and_load] Could not retrieve index file for 'input_filtered.vcf.gz'
Working on 2 samples from 2 families

# Working on contig chr21 in individual HCC1395_BL
Found 141 usable heterozygous variants (0 skipped due to missing genotypes)
Number of supplementary alignments: 0
Number of non-singleton groups: 2453
Skipped 0 groups
Found 11082 reads covering 141 variants
Kept 1851 reads that cover at least two variants each
Selected 258 most phase-informative reads covering 51 variants
Best-case phasing would result in 18 non-singleton phased blocks (0 singletons). 
Phasing 1 sample by solving the MEC problem ...
Largest block contains 8 variants (15.7% of accessible variants) between position 10462806 and 10462873

# Working on contig chr21 in individual reference-NA12878
Found 12 usable heterozygous variants (0 skipped due to missing genotypes)
WARNING: Sample 'reference-NA12878' not found in any BAM/CRAM file.
Found 0 reads covering 0 variants
Kept 0 reads that cover at least two variants each
Selected 0 most phase-informative reads covering 0 variants
Best-case phasing would result in 0 non-singleton phased blocks (0 singletons). 
Phasing 1 sample by solving the MEC problem ...
No. of phased blocks: 0
WARNING: Ignoring existing phasing information found in input VCF (PS tag exists).

# Resource usage
Maximum memory usage: 0.168 GB
Time spent reading BAM/CRAM:                   16.1 s
Time spent parsing VCF:                         0.0 s
Time spent selecting reads:                     0.2 s
Time spent phasing:                             0.4 s
Time spent writing VCF:                         0.0 s
Time spent finding components:                  0.0 s
Time spent on rest:                             0.1 s
Total elapsed time:                            16.9 s