After creating your new blank disk and formatted it did you select 'Save disk' in the disk drives dialog? I guess so since you can then load it into D1.
I used the LIST command which is just a different way of saving. LIST creates a listed text file, SAVE creates a tokenised BASIC file I think. To be honest it's been a while. Shouldn't make any difference. Make sure you have it set to R/W in the drives dialog (not virtRW).
Quick tip for cassettes (and you may already know). Often you need to advance the tape beyond the clear or coloured leader before you try to load. Use your finger or a pencil in the right hand sprocket of the cassette and wind the tape forward until you see the brown oxide tape at the bottom. Then put it in the 1010.
Some games require START to be pressed as you boot the Atari, often they'all need OPTION too which disables BASIC. If your games have inlays check the instructions. (It's worth trying with both START and OPTION as early games pre the XL line often just say START as the 400 and 800 didn't have BASIC built in)
Even if you do manage to get them loaded you'll probably want to move to a more modern storage method and any of the suggestions above are good.
Is anyone else having issues accessing the forums. For the past few weeks I've seen very slow load times and frequent server timeouts. I've tried multiple browsers, clearing cache etc but they still persist. Just wondered if it was a know issue or something local here. My connection if fine and I don't have problems anywhere else.
The loader has a CIO FAT file system, so you absolutely should be able to flash the firmware from the XEX loader, but if it's not working, I've either broken something, or your Incognito needs a CPLD update (not coincidentally, the old CPLD code didn't allow flashing from the loader).
I'll try on my Incognito tomorrow to be sure. I'll check U1MB as well, since during development I do all the flashing over SIO2PC.
It may be that I'm running the original CPLD code. IIRC this Incognito was one of the first batch. *SIGH* this is what you get for being an early adopter!
I finally bit the bullet and sent a membership request a few days ago. The fact that the magazine is in German and my German is rusty to say the least had always put me off before, but so many English speakers have recommended membership I decided to go for it.
I've shipped XLs simply wrapped in several layers of bubble wrap and an outer layer of plastic. As others have said the main issue is separate items in the box acting like projectiles. If I ship anything with a power brick, I usually wrap it in bubble wrap and tape it to the floor of the box.
Note the instructions say to "remove cartridges" then hold down start while turning on the computer. Since removing carts on an 800/400 would mean no chance of BASIC being installed, on an XL/XE you'll need to hold down START and OPTION when you turn on the machine. Option disables BASIC and START tells the machine to boot from cassette. The other thing I would do is manually advance the tape beyond the leader so that you can just see the brown oxide of the actual tape at the bottom of the cassette before you load it into the deck.
When you turn on with start + option held you should hear a beep. Release the keys and press play on the tape deck followed by return on the computer.
EDIT: Just noticed you're using a 600XL so tested the cas image in the emulator using 16K and it loads OK so no issue with too little RAM.