When viewing your list of crashes in Crashlytics, always study three things: 1) Is it filtered to a specific build or not. 2) Is it filtered to the right event type or not (Crashes, Non-fatals, or All). 3) Is it filtered to a narrower than max time range or not (i.e. crank it up to "last 90 days" or maybe an even bigger custom range).
Looks like your list is just for your build 7.6.0. I can't see what time range you have it set to.
Crashlytics web page tries to remember your last used settings in these regards - so when you change them temporarily while studying one issue, then tomorrow you come back in expecting to be seeing everything, it'll still be stuck on your narrowed down filter. Drives me nuts.