Oh! I just noticed that your copy of Affinity Publisher is the old beta; this file might use features that weren't available in the beta, rendering it unopenable. I suspect that's probably the issue, but I'll still ask around just in case.
I think so, yeah, sorry. I haven't found anybody else running the beta to double check this with, but I've checked with others running the latest version of Affinity Publisher, and they're having no problem.
