Why does these things happen?

[synthsin75]

You'd need to post a link to the problem file for us to really diagnose the problem. Otherwise, we could guess forever.

[jeremiahbabers]

i found a weird work around where i opened the characters in a new file and added the smartbone tweaks.

then i saved the characters to content folder.

i loaded that character in my original project and it saved the keyframes

[jeremiahbabers]

ok so i animate the bones in smartbones, save, close, then return with no animation in the smart bones

https://youtu.be/J18A8WNqHL0

[synthsin75]

Since that file seems to be running so slow, it's probably pretty big. You might want to consider breaking it down into smaller scenes, getting a faster computer, or giving Moho more time to complete the save, before closing the file.

Just some ideas, as I've never seen that happen myself.

[Daxel]

Yep that doesn't look right. I would check for the usual problems that cause big performance hits: corrupted references and negative keyframes. In this same topic you have how to solve negative keyframes. And you can solve corrupted references by just deleting your references and creating them again. Of course, if your PC is very weak and your scene is massive, that could be the problem as Wes suggested.