However I am posting this now because there is an actual (different) related glitch, and I have found a solution to it. (Note the glitch is not poor programming by the developer(s) but just how the system works)
Glitch:
1. Trigger: loading a save state from a previous custom time
2. Result: separation of the in-game save from the savestate
Sometimes this seems to also be triggered randomly without loading from a previous savestate custom time, however I can't confirm this.
AKA:
1. Trigger: You save the game on Christmas Eve, you change the date to Christmas play it and save. Then remember you needed to do something back on Christmas Eve so you load the Christmas Eve savestate
2. Result: You play the Christmas Eve save just fine, but now when you change the date back to Christmas, the game acts like it is brand new with no saves.
If you don't need to change the date, then this glitch won't be an issue for you. However on games like Animal Crossing where changing the date is important, it becomes an issue.
Behind the scenes issue: the in-game save has become separated from the game itself. However there is still (by default at least) an in-game save within the savestate.
Solution: (10 minutes of moving/copying/renaming files)
First force stop the DraStic app (reboot your phone if you don't know how to force stop apps)
Then get a file explorer for your phone. If you don't have one I suggest "Amaze file explorer".
Find the game file (you had to download it yourself) or download the game again. For example Animal Crossing.7z
Make a copy of the game file with a new name. Ex: Animal Crossing 1.7z
Find the DraStic folder. It will be near your downloads folder.
Go to the savestates folder within the DraStic folder.
Find the savestate for the game you want to load. I suggest using the "properties" option on the files to find the one that has the same date/time as the savestate you want to restore.
The name of the file should look something like this
#### - GAMENAME_#.dss
Example:
0389 - Animal Crossing - Wild World_9.dss
Make a copy of this file and rename GAMENAME to whatever you named the new copy of the game.
For example remember the name we chose above was Animal Crossing 1.7z
so we would change
To0389 - Animal Crossing - Wild World_9.dss
All we did was add a " 1"0389 - Animal Crossing - Wild World 1_9.dss
Then open up the DraStic app
Select "change game"
Select the new copy. Ex "Animal Crossing 1.7z"
(If continue is grayed-out see REF 1 at the bottom otherwise keep reading)
Select "continue"
Perform an in-game save (different for each game)
This will re-attach the in-game save to the new game. However if you restore a previous custom time savestate again, you will break the game again and have to follow all of these steps again.
REF 1: if you don't see the "continue option" try fiddling with stuff. For example close DraStic completely and reopen it. Try rebooting then doing it, try loading another game then loading the game you want, try refreshing your files on the file explorer to make sure all the files are there. This should solve the issue.