Three Late Dormancy-Breaking Trees: Trouble? Or Normal? Late April 2020

We have three young trees that were all bought as nursery stock that haven't broken dormancy in our yard.  On a walk around the yard yesterday, I was surprised by the small Chanticleer Pear tree that had not joined the other ones in flowering out.  Below, you can see that tree for garden diary reference.  

Here's one of the buds on the tips of the tree.  I've scraped away some of the bark and I see plenty of green underneath it, so maybe this one is just late in waking up? On the other hand, why isn't it showing even ONE flower?  The tree across the yard is in full bloom.  That has me concerned.

The Crimson King Maple tree is also showing no signs of life.  If I look around at other Maples, I see some buds bursting open on *some* of the tips, but a further look around the neighborhood and I see plenty of trees that haven't broken dormancy yet.  A scrape on this one shows a little bit of green, but the tree itself feels a little 'hollow'.    This one has me concerned the most.  Compare it with these photos that were taken in the second week in May. 

Finally, the tiny Red Valley Sun Maple tree also is not showing any leaf'ing out.  The tips have buds, but I'm not seeing a lot of life. 

I mostly wanted to put this here in the garden diary so I remember next year to just have some patience if these are simply slow-to-wake-up trees.