[GeoffAirey]

What happens when you search for one of the actions which is 'lost'

you may find that either
1) you've checked them off accidentally, especially if they are sub actions or in a project
2) They are set as a status such as 'on hold' which would not show. I'd tap on the eye at the top right of the screen and set it to 'all'

I'm not saying you haven't lost them. just that there are more obvious explanations which may be true.