Someone posted in another thread that support was having issues with their email system and was behind. So patience is needed currently.
Asside from their current email issue, I've had varied response times on the occasions that I've contacted them. Sometimes it was next day, other times it was a couple days later. It's only one developer and I'm sure he's busy with other things too.
Probably got lost in the deluge of emails he received with a recent update that caused some issues. Just remember it’s a single person doing all this ( developer/support/sales person ).
You could also try posting your problem here to see if the literally thousands of people with Blue iris could provide an answer (especially if its a simple or common problem).