Hello, I've ran an imputation job successfully. However, I thought match:0 is strange. What does it mean exactly?

Skip allele frequency check.

Calculating QC Statistics

Statistics:
Alternative allele frequency > 0.5 sites: 296,279
Reference Overlap: 100.00 %
Match: 0
Allele switch: 345,554
Strand flip: 0
Strand flip and allele switch: 0
A/T, C/G genotypes: 20,993
Filtered sites:
Filter flag set: 0
Invalid alleles: 0
Multiallelic sites: 0
Duplicated sites: 0
NonSNP sites: 0
Monomorphic sites: 0
Allele mismatch: 1
SNPs call rate < 90%: 0