Hello, everyone.
Happy New Year!
We've found a crash error in Unity 2021.2 and above on both UModeler and UModeler Lite. It occurs when you create a UModeler object and undo it.
That bug above and another bug regarding Serialization Depth bug have been fixed finally . See the following change list.

Version 2.8.10f2 - December.14.2021
• Asset : Includes the Moonglow Village Demo Package for 2.8.10 users.
• Fix : Fixed an issue where the several same online document windows pop up when the mouse is over a text menu item in UV Editor.
Version 2.8.10f3 - Jan.3.2022
• Asset : Includes the Moonglow Village Demo Package for 2.8.10 users.
• Fix : Fixed a crash error when undoing creating UModeler object in Unity 2021.2.1 and higher versions.
• Fix : Fixed a warning issue regarding "Serialization depth limit 10 exceeded" caused by the codes of Mirror Cancel Function which was implemented in 2.8.10. The cancel function of the mirror tool has been reverted so it won't be available for now till we'll find a solution.
• Fix : Fixed a .obj exporer bug where multiple materials in the exported UModeler object couldn't be imported in Unity.