GATK haplotype caller: discrepancy between AD and GT

Hi

We have come across a few calls as below, where the winning PL and genotype point to 0/1, yet the AD shows
zero reads supporting the ALT allele. Is this expected, or is it a bug?

chr1 726136 . TGGAA T 123.73 . AC=1;AF=0.500;AN=2;DP=38;FS=0.000;MLEAC=1;MLEAF=0.500;MQ=49.50;MQ0=0;QD=3.26 GT:AD:DP:GQ:PL 0/1:30,0:30:99:161,0,15526

thanks
Severine