Hello, my apologize for the delayed answerback, we are experiencing a backlog at these days, and I commit a mistake I test only the mcuboot_opensource and that was the image that works for me.
At these days I still having doing testing on this both examples, but I have the next message error.

This behavior is different that you present. Could you let me know the command that you are using to sign the image?
I did the test with the next one.
"imgtool sign --key sign-rsa2048-priv.pem --align 4 --header-size 0x0400 --pad-header --slot-size 0x200000 --max-sectors 800 --version "1.0" app.bin app_binary_SIGNED.bin"
The version of SDK is the 2.16 and the IDE 11.9.1.
Could you add more information about your steps to replay your issue?
Best regards,
Pavel