On the gnomAD vcf file there is the filter field containing the following information:
##FILTER=<ID=AC0,Description="Allele count is zero after filtering out low-confidence genotypes (GQ < 20; DP < 10; and AB < 0.2 for het calls)"> ##FILTER=<ID=InbreedingCoeff,Description="InbreedingCoeff < -0.3"> ##FILTER=<ID=PASS,Description="Passed all variant filters"> ##FILTER=<ID=RF,Description="Failed random forest filtering thresholds of 0.055272738028512555, 0.20641025579497013 (probabilities of being a true positive variant) for SNPs, indels">
Using PyVCF works fine for all other fields (pos, ref, alt and info). However for the filter field, for most of the variants I get the empty list:
print(variant.FILTER) # will print: 
For a scarce amount of variants I get ['AC0', 'RF'] or ['ACO'].
Does the empty list mean that the FILTER is PASS as shown in the function: _parse_filter() in the parser code?
My installed PyVCF version is 0.6.8.
Thank you and keep safe!