I've been using Google Maps for years to track my travel history, to confirm where I'd been and for how long on certain days. Unfortunately I had a panic attack about a week or two ago when I discovered that my entire history was wiped out entirely. I tried everything from rebooting, disconnecting the account / reconnecting, clearing cache, clearing app data, etc., etc..
What worked for me was adding a second Google account that had never used maps on the phone and immediately my entire history returned. So Google didn't exactly wipe it out, they just made it inaccessible to the primary account that was 'connected' to the data... and somehow accessible to a brand new account that never had seen the data. Weird. But it worked.
I'm sure there's a lesson here not to trust Google after all the products they've destroyed over the years (like Nest, Withings, etc.) but I really thought they'd never do the thing that they did here, I never thought they'd wipe out my travel history.