Hello Andy,
What I do is save regularly eg every 15 mins or so.
Also, Use the F10 to backup your files regularly, this backs up your xml files including the rgbeffects file where models have been defined.
Finally , save any changes to models 9save on the layout tab) or close xl at every session or sooner becuae then it will prompt you to save your timings models etc.
I do so everytime I get up if I have been using xl , but that is also because my (work) laptop has this nasty habit of installing software and then rebooting when i am not looking.
Also ending xl and restarting it at least once a day ensure that buffers used for Undo etc are cleared out.
Could your issue be because of Visual studio - what are you using that for with xl ?
You also need to ensure that you see which timing track is active (look at the circle against it) and/or have only one of that selected.