With Version 3.4.5 (Curse) this LUA Error pops up when trying to import, rename or delete:

1x ...aceMythicDungeonTools\MythicDungeonTools-3.4.5.lua:2637: attempt to index field 'dataImportDialog' (a nil value) [string "@MythicDungeonTools\MythicDungeonTools-3.4.5.lua"]:2637: in function HideAllDialogs'
[string "@MythicDungeonTools\MythicDungeonTools-3.4.5.lua"]:2642: in function OpenImportPresetDialog' [string "@MythicDungeonTools\MythicDungeonTools-3.4.5.lua"]:1291: in function <...aceMythicDungeonTools\MythicDungeonTools.lua:1290> [string "=[C]"]: ? [string "@Ace3\AceGUI-3.0\AceGUI-3.0-41.lua"]:72: in function <Ace3\AceGUI-3.0\AceGUI-3.0.lua:70> [string "@Ace3\AceGUI-3.0\AceGUI-3.0-41.lua"]:306: in function Fire'
[string "@ace3\AceGUI-3.0-41\widgets\AceGUIWidget-Button.lua"]:22: in function <...dOns\Ace3\AceGUI-3.0\widgets\AceGUIWidget-Button.lua:19>`

fixed