One of the reasons that retailers are out is the federal government has declared eminent domain over protective clothing in order to make sure the supplies are going to healthcare, first responders and other critical sectors.

Another major issues is the Strategic National Stockpile was severely depleted over the last decade and not replenished. So there weren't enough supplies that healthcare and first responders were told they could rely on in a disaster or crisis.

The problem is getting solved, it just isn't something that is going to be fixed overnight. Reputable manufacturers are revamping their production to make the needed masks and other PPE, once they get going the supplies will become available.
"Trust in God --and press-check. You cannot ignore danger and call it faith." -Duke