GATK mutect2 failing on gnomad input size determinatino

Hi,

I am running GATK's mutect2 on FireCloud. I am using the value "gs://gatk-best-practices/somatic-b37/af-only-gnomad.raw.sites.vcf‎" for the attribute gnomad. I am receiving this failure message:

Failed to evaluate 'Mutect2.gnomad_vcf_size' (reason 1 of 1): Evaluating if defined(gnomad) then ceil(size(gnomad, "GB")) else 0 failed: gs://gatk-best-practices/somatic-b37/af-only-gnomad.raw.sites.vcf‎

Is this a known issue? Any help much appreciated, thanks.

-Eric