I've recently gotten interested in creating my own Campaign, and are learning about Dungeon Maker by following SirMadness TV's very helpful DM series.
Although I am a new user of the Dungeon Maker, I'm sure this bug report isn't caused by the typical new-user finger trouble.
In SIrMadness's Tutorial 7, he starts developing a Campaign (as opposed to an individual Location), setting up a few Custom Items, Custom Monsters, NPCs, etc. All was going well with my slavish copying of what he was doing, until we got to (Custom) Loot Packs.
Following SirMadness's instruction, I clicked on "+ New Loot Pack", used the same "Internal Name" he did, and the same "Title". Then I did "Add Item" twice, to add two of the Custom Items SirMadness and I had already set up in our new Campaign. Then I hit "Apply".
The Campaign Creator page, under "Loot packs (1)" had the entry for my just-created pack, but it had the fatal error signal (an exclamation mark inside a red triangle) at the far right of the row. When I moused-over the warning, the popup read: "The internal name for this content clashes with that of another user content or internal Solasta content. Chose [sic] another internal name."
Note that this is the ONLY loot pack I have created, so it can't be clashing with anything else I've created. Nonetheless, I have repeatedly deleted the loot pack and recreated it, using many different "Internal Names", including the default of "LootPack1", and 20-character random messes chosen by rolling both of my fists back and forth over my keyboard. I have also tried creating loot packs with no items at all, so just with the Internal name and title fields filled in. I invariably get the same error triangle.
It's a fatal error, because when I create Chests containing the Custom Loot Pack, and playtest it, the chests are invariably empty when I had added several items into the loot pack.
I have loaded down and played a lot of campaigns created by other people, but I can't imagine that my new loot pack is clashing with any of them, especially because I tried some truly random internal names, and SIrMadness has me working within a Campaign of our own creation, not importing someone else's first.
Also, I usually run the "AlwaysAlt" mod, but turning it off and emptying the Mod folder didn't fix the problem.
I'm using Solasta "Version 1.4.33 - Public". If it helps, Steam says the App ID is 1096530, Build ID is 10260630.
I'm impressed by Dungeon Maker and am looking forward to eventually writing my own creations.