I did that with last batch (no pressing), dried on cardboard for 2 weeks and as soon as it was packaged by the dispensaries it molded in 2 days. Maybe I'll try storing it with desiccant packs.
Wow, sounds like maybe a high concentration of spores floating around? You could package inside an ozone-filled glovebox. Or on a more serious/practical note, perhaps hit everything with a germicidal UV bulb/wand before you bring it in to vend? I've played around with dessicant quite a bit and really think it should solve your problem so long as the hash is packaged dry. Don't use the auto rh ones that work nicely for buds, just straight silica-gel paks like what comes in vitamins (buy bulk online). You can get similar sized oxygen absorbers too, prob not necessary but I use both for aging some fine-grade personal hash long-term (months/years).
I also realize some of my posts probably sound kinda wacky, but I do have considerable experience processing concentrates and have dealt with mold at various stages on a few occasions. Fortunately my ambient workroom rh is usually around or below 50%, so if your environment is more humid, extra precautions are probably in order. Some people dry it with a little heat (like carboard on top of a t5 or maybe a food dehydrator on low), but I'm picky about not pre-decarboxylating and prefer to err on the cooler side whenever possible.
With icewater extraction there's a lot of room for personal curing preferences and some folks really enjoy that 'old-world' warmed/pressed flavor profile (which the more middle-aged to elderly among us might tend to generally associate with the term hash prior to the dispensary movement). Having access to so much of it before packaging, I now prefer the freshest most un-disturbed dry forms possible, mostly run from fresh-frozen material now thanks to conversations with Graywolf and others here. That little twist can really improve quality and makes processing a lot more convenient too.