So the May 2020 issue of Modern Drummer is the Neil Peart tribute issue.

Single issues were sold out almost immediately on their web site, or at least showing as out of stock.

I found another web retailer that had it - ordered the two copies I need (one for my buddy) a couple weeks ago. Today, I got a message that they were unable to get info from Modern Drummer about availability, so the order was cancelled. As of now, all the usual local outlets are closed. There's one B&N that might be doing curbside delivery, but I haven't had a reason to be anywhere near there, so I haven't called yet.

Anyone have any ideas?

I don't know about in the U.S., but in Canada I see Modern Drummer stocked at Walmart.
If I get there this week, I will check for you. I don't go as often as I used to because I find stores fairly unpleasant places right now.

Thanks, Jason. Other than grocery stores and pharmacies, we've been avoiding stores. My next chance to get near that B&N will likely be Friday. We'll see.