Greetings Exile,
Thank you for your report. Could you please try to restore a backup of your saved file?
You can find it by following:
Steam\steamapps\common\Conan Exiles\ConanSandbox\Saved
It should be the “game” file for Exiled Lands or “dlc_siptah” for Isle of Siptah.
Please make sure to back up your current saved file before replacing it with one of the “game_backup_X” files. Edit the name of the backup to match the above accordingly to the map you’re playing and try to load singleplayer again.
Thank you in advance.