Indeed, no concept of Project Management.
We all know cock ups and delays can happen, especially when you have to rely on other suppliers and third parties that may not be as committed as you.
So just going quiet is inexcusable and raises alarm and suspicion.
It only takes a minute or two to say -
"Sorry guys but one of our suppliers has caused a delay so we wont be progressing as planned. Will let you know as soon as things are back in plan!"
"Sorry guys but one of the shipments didn't come up to spec on the QA side so we've had to order in a fresh batch! Hopefully back up to speed in a week or two!"
Now that didn't hurt did it?!
Keep your backers and investors informed. Silence just makes it look like you ran off with the money.