Game crash when saving in live mode

M0usseux​  First, the easy part.  Saves are named in the format Slot_xxxxxxxx.save , where the Xs stand in for hexidecimal digits (0 to 9, a to f).  There must be exactly eight digits, and no extra characters in the name.  So what you're seeing is fine if there are seven zeroes and not only the six you've written.

The .verx extensions denote backups of the main save with the same name, and if you change the number (so it doesn't conflict with another file) and delete the .verx , this backup will now be a viable save that you should be able to load from the Main Menu.

When you say you can only load a few of your original saves, do you mean that they don't show up in the game, or that you can select them but the game crashes or otherwise doesn't load into the saves?

For the crashing, please let me know whether your user folder is in OneDrive.  Here's how to check:

https://sims4.crinrict.com/eng/2018/07/how-to-find-your-user-folder/

Please also provide a dxdiag.  Click Windows key-R, enter dxdiag in the run box, wait for the scan to finish, click "Save all information," and save the file to your desktop.  From there, you can attach it to a reply using the paper clip (Attachment) icon included with the other formatting buttons.