You probably have the maps somewhere. Equip them on fodder characters (your army of Heavy Knight lifters for example) to increase the chance of encountering pirates btw (the units don't need to be deployed to get the effect). I think you can check which maps you are missing at the Data Shop.

To clarify what I said, I checked every character's equipped items, and the maps I mentioned aren't there. They are also not in my bag or my warehouse. They do show up in the Dark Record (that was a good idea, thank you).

In the Dark Record, I can see that I have never seen the Red Pirates map, so I guess I will go diving to 41+ and hope for the best.

My first thought is they might be equipped on a character who isn't in your party. Like if you started a new cycle and didn't recruit that character yet on your current one.

Maybe you put those maps on a character that you have to unlock again, like a story or DLC character after starting a new cycle, or maybe you put them on Asagi and switched to her other form. In any case, it's probably not permanently lost.

That's brilliant, folks! I will re-unlock some people and see what I can find. Thanks!

Unlocked all the summoning experiments characters and found 2 of the 4 missing maps in their equipped items. I am guessing the other missing maps are equipped on Axel-mode-specific characters, so I will have to swap over to grab those.

Thanks again for the quick replies!

I've noticed some of my gear going missing at times due to characters being unavailable from starting new cycles, too. Realizing you left a map or a nice piece of gear on someone that joins after several chapters or meeting certain conditions (like Yukimaru or Raspberyl) can be frustrating.

Note that once you have access to the Land of Carnage, you won't need to swap Modes to get access to the Axel Mode specific characters. If you've reached Adell's last story map (without fighting the last battle), Axel will be available to recruit for Land of Carnage use and Axel's storyline allies can be individually recruited by Adell's Senator Bills in the Dark Assembly.

Replying one last time to say I tested the logic by finding the Red Pirates first. Even though I did not have the last two treasure maps in my inventory, since I had found them previously and they were in the Dark Record, the Land of Carnage unlocked immediately.

That way I don't have to beat Adell mode to get to Axel mode, unless I later feel like it for achievements.

Thanks again for all the help!