It's May 31 at the time of writing. I logged in to find that my 555 day streak had reset to zero despite my streak freeze being active, and that my monthly progress was listed at 0 XP even though I know that's wrong. My profile suddenly lists no progress or achievement info. Is anyone else having this issue?
I've just looked at your profile. Your streak is only one day, but the rest of your progress is showing up - level 18 in French, etc.
The three most common reasons for losing a streak are:
you're working on a phone or a tablet, and your phone / tablet hasn't been able to synchronise its data with the server.
your daily target is set to more XP than you did yesterday.
you've travelled across timezones, and Duolingo's using the time zone you travelled from.
The first is the most likely - that your mobile device hasn't synchronised.
It's always a good idea to buy a streak freeze if you care about your streak, and to check every now and then that it's still active - often they get used without us noticing. It's also a good idea to use the website to check that your phone / tablet has synchronised with the server.