In original game quick save and checkpoint don't work. Quick load crashes the game. Only option is to save and load manually.
There is no such problem in Suffering TTB.
System is Windows 10, any clues why such thing happens?

Same problem here, I tried installing it to my smaller 2TB harddrive and that fixed the problem. It seems if you try installing it on anything bigger than 2TB you get this problem.

I have been unable to reproduce the checkpoint problem on my end, but the first game has no quick save/quick load feature AFAIK. Maybe you accidentally hit F10 key, which is for making screenshots and it's broken in the first game. The screenshot key can't be re-assigned, but it works in the second game and outputs a screenshot in the installation folder.

I don't know how to fix the screenshot feature in the first game, so I just disabled it in my patch so at least it doesn't crash: https://www.gog.com/forum/the_suffering_series/the_suffering_series_aio_unofficial_patch

My hard drive is 1TB and it doesn't saves too. Totally disappointed how's the game made Win10-compatible by GOG.