@Yarat I think ther's a problem with the AntiVirus engine or maybee
Password protected archive, Maximum number of extracted files reached, Maximum nesting level reached, Maximum unpacked size reached, Maximum decompression ratio reached, Gzip max decompressed file size or something similar.
"failed to process the file" means the engine was not able to scan these files.
And additional as @PhoneBoy mentioned, you don't allow acces to internet for these clients but these logs states you allow. Check your rulebase.