When creating a picture, I got a bundle with the maps, but I can't open it in survival. I right-click it while holding it as you would do with any other bundle, and it doesn't drop the maps. I checked if any other bundle has that issue, and it only happens with the bundles that this mod gives me.

The bundle is bugged because it contains maps that aren't stackable since they're different, aka one map would take up the whole bundle due to the bundles' mechanics.

Update - The bundle won't open in survival, but if you switch to creative - it works as intended.

I believe it's on purpose.
This issue is from some months now, but I leave this here for any other person who might end up looking for help on the same issue:

You can't get the maps out of the bundle. However, right-clicking the bundle on an item frame will place the maps automatically. You have to make the specific frame size for it to fit, and you can not retrieve the maps back. The bundle disappears too.

I believe this is a measure to avoid having players dupe bundles.