Firstly try to use chainload to boot .efi files.

INSTALL/grub/grub.cfg

@@ -113,7 +113,7 @@ function get_os_type {
     
     for file in "efi/microsoft/boot/bcd" "sources/boot.wim" "boot/bcd" "bootmgr.efi" "boot/etfsboot.com" ; do        
         if vt_file_exist_nocase (loop)/$file; then        
-            set vtoy_os=Windows
+            set vtoy_os=Windows            
             break
         fi
     done
@@ -1445,22 +1445,22 @@ function efi_common_menuentry {
         vt_vlnk_dst="${vtoy_iso_part}${vt_chosen_path}"
     fi
     
-    vt_concat_efi_iso "${vt_vlnk_dst}" vtoy_iso_buf
-    
     ventoy_debug_pause
-    
+
     ventoy_cli_console
+    
+    #first try with chainload
+    set vtOldRoot=$root
+    set root=$vtoy_iso_part
+    chainloader "${vt_vlnk_dst}"
+    boot
 
-    unset vtoy_dotefi_retry
+    #retry with isoboot
+    set root=$vtOldRoot
+    vt_concat_efi_iso "${vt_vlnk_dst}" vtoy_iso_buf    
     chainloader ${vtoy_path}/ventoy_${VTOY_EFI_ARCH}.efi memdisk env_param=${env_param} dotefi isoefi=on ${vtdebug_flag} mem:${vtoy_iso_buf_addr}:size:${vtoy_iso_buf_size}
-    boot
-    
-    if [ -n "$vtoy_dotefi_retry" ]; then
-        unset vtoy_dotefi_retry
-        chainloader "${vt_vlnk_dst}"
-        boot
-    fi
-    
+    boot    
+
     ventoy_gui_console
 }