To-Do Tasks Deleted in Browser After Deleting Cache & Cookies

I use the New Outlook for my emails, and use the web version of To-Do to write down my tasks. A few other people at my company use this app as well. I love To-Do for it's simple UI and how easy it is to jot down a task and triage it. Unfortunately, I ran into a rather troubling problem that I'm worried could impact my ability to maintain a solid workflow while using To-Do.

Recently, I deleted my browser history, including my entire cache and cookies. When I did this, I found that all my To-Do tasks other than those created that day were gone.

I browsed the forums for a bit, but found nothing that could restore my deleted tasks. Eventually, I thought to try using a different browser. After logging in using Chrome, I found all my tasks were still intact, but the tasks I had created the day I deleted my cache & cookies were not there.

I find this to be strange. Anyone else experience anything like this? Or does anyone know why this might be occurring or how to re-sync tasks between Edge and Chrome after a cache & cookies purge?