I also noticed 3 weeks ago, that saves stopped work. Restarting game moves 1 hours or 3 hours back to old save. Some cases (about 10%) I was lucky to save, during space travel.
Game session starting April 2019, opened all 7 planets, 3 planets Gateways finished .
FOLDER c:\Users\%USERNAME%\AppData\Local\Packages\SystemEraSoftworks.29415440E1269_ftk5pbg2rayv2\SystemAppData\wgs\00090000036E464D_6C0B0100B10345C3B55AA1C421DDC84D\063F9895F349450F8B83E783E09EA965\895E8F688C0D4D209FC1CACF0C7334A8 file now is 15.9 MB size.
I started new game for scratch, then saves is working. That smaller new account game save file is 0.9 MB size.
I am very upset, than old save game is broken. So now i am press "UNINSTALL" game. I hope in two/three months lazy devs will found cause of problem.
I am rated yours game 1 stars of 5 now at Windows store. I hope later I can change my rate.
Astroneer version 18.104.22.168 Windows Store (UWP).
OS: Microsoft Windows 10 Home 64-bit
CPU: Intel(R) Core(TM) i7 CPU 920 @ 2.67GHz | GPU: AMD Radeon HD 7700 Series | C:\ SSD disk INTEL SSDSCSSW180A3 (SATA/300).
Motherboard: Gigabyte Technology Co., Ltd. EX58-UD4P | Resolution: 1920 x 1080 .
Yes it's old 2008ths PC, but Its working, game stabile, not crashing.