Resume stalled Apple Watch app update
I noticed that even though the transitional icons are showing up on the Apple Watch, on the Apple Watch app the "Show App on Apple Watch" option was turned off for those apps. Turning on the option restarts the download. In any case this appears to be a bug.

Although this works, it can be slow to attempt to figure out which apps aren't downloaded and turning on the option, perhaps someone could suggest a more efficient method. Also, @user24601's suggestion might be something to try.