Maybe this isn't the right place to post this, as it was a different game, but I completed a number of things in Merge Academy that were all un-done when I returned later! Played around 12-1 pm ish (central time).
In Grid event I uncovered a tile, got one more of the items in my next order ready, generated at least 100 items.... In Main event, I generated and merged a minimum of 100 items. Outside of the two grids, I collected all of the every-12-hour rewards (and put them on the grid), opened a purple sticker pack... Now, because those activities are in separate parts of the game, if it was a simple forgot-to-click "Save & Exit" (ignoring the fact that I am up to Rank 46 and know how it works) it should not have LOST that amount of activities completed.
Came back at 4:41 pm. Not only was it showing the map with the exclamation point (which should not be back for another 7 hours) my energy in both Main grid and Grid event were at 1. If I somehow got disconnected and stuff was lost earlier, why did my energy not start regenerating while I was gone??? It did at least let me re-open my purple sticker pack, but all the other merges I did earlier were just rolled back as if I never did them!
Original activities were on Laptop, Windows 11, Chrome Version 156.0.8078.48
Sign-on when I discovered everything missing was iPhone iOS 27.0. Confirmed on laptop the fact that items were NOT there, my energy was not full, and it does not recognize me already gathering my freebies 6-ish hours ago.
To clarify: I received NO error messages, no disconnection issues, no indications of any problems. When I left the game it seemed fine. When I returned it seemed fine - just to a PREVIOUS stopping point, not my most recent one.