Something is killing my sugar maples. Any ideas?

I am a backyard boiler that makes about 7 gallons a year. In the past two years about 1/3rd of my 10 maple trees in the yard have developed this malady (see photos). Large chunks of bark have just dropped off, typically at the base-root of the tree but then also further up the tree. They look absolutely dead at that part of the tree. I have asked my forester and Gerlach’s landscaping if they’ve ever seen this before and they said no. I didn’t tap last year thinking I didn’t want to stress the trees further . Any ideas? Attachment 22549Attachment 22550Attachment 22551

It is exceedingly hard to diagnose issues without seeing it first-hand or having a conversation about it. Without any other photos or description, my two guesses would be:

1. Lightning strike on several trees in one area followed by secondary infection of Armillaria shoe-string rot, OR
2. Eutypella canker, perhaps with a secondary infection of Armillaria or some other fungus.

Might also be something like sapstreak disease. As I said...hard to tell without seeing it up close.