I'm having this problem with autosave. I make a change, such as adding a description to an era, then I wait for the green autosave checkmark in the corner before moving on. When I go back to that era, the description is gone.
It's most egregious when trying to change an event's column. Sometimes it won't move to the newly-selected column at all, other times it moves successfully but reverts the next time you click on that event.
Here's a screen recording of it happening:
https://www.worldanvil.com/i/7589974 The same thing happens with any other change, not just description and not just starting eras.