DFU over USB get stuck in MCUBOOT after power cycle

Question

Hi,

NCS3.0.2 on nRF52840 platform. 
 Using mcuboot + app build using sysbuild 
 in the app: shell + console are configured over cdc_acm_uart1 (connecting to e.g. COM11), mcumgr configured over cdc_acm_uart0 (connecting to e.g. COM10) 
 mcuboot boot is configured over cdc_acm_uart0 (COM10) 
 
 The app includes the following code fragment in its main thread (right after system initialization: 
 
 LOG_INF ( " application starting... " ); 
 app_start (); 
 LOG_INF ( " application started " ); 
 
 if ( ! boot_is_img_confirmed ()) { 
 LOG_INF ( " confirming image... " ); 
 int rc = boot_write_img_confirmed (); 
 if ( rc != 0 ) { 
 LOG_WRN ( " Error confirming image failed. Error: %d 
 " , rc ); 
 // sys_reboot(SYS_REBOOT_COLD); 
 } 
 } 
 
 LOG_INF ( " application main thread exiting ! " ); 
 return 0 ;

I try to DFU over USB. 
 I closely followed Lesson 9 of the NCS intermediate course. Specifically exercise 4 
 
 I build the application + mcuboot and then flash them through the IDE (vscode). 
 After flashing, the app runs as expected. I even managed to update the app with mcumgr (using AuTerm). 
 It all works fine even after running "kernel reboot" shell command. 
 
 BUT, when I power cycle, something weird happens and I only see "MCUBOOT" in the serial monitor list of devices. 
 The update does not survive a power cycle. 
 
 Strangely, when I use AuTerm to probe the image list, I get no image identified... (no hash, nor flags). 
 I do see the image in place using the nrf programmer 
 
 Some more info - I use a custom nrf52840 based board + custom private key (as explained in exercise 2) 
 
 What can be the reason ? 
 Attached are sysbuild.conf & sysbuild\mcuboot.conf 
 /cfs-file/__key/communityserver-discussions-components-files/4/6114.sysbuild.conf 
 /cfs-file/__key/communityserver-discussions-components-files/4/7522.mcuboot.conf 
 
 We are starting production of poc units and I don't have DFU in place