Well... you are missing some of the "detail" of your situation there the beast. You say you are loading a Saved game, I assume, but had you exited the program after doing the Save, or is this just a Save and immediate re-load? How big of a task force was this, were there airplanes, were you submerged? In other words, was it ~really~ busy up top, or just a little? After you hit the Save menu, did you Name it a new, unique name, or just Save on top of where you were? After completing the Save dialog and actually "Saving" the game, did you pause a moment, and make certain the game was finished doing the writing to your hard drive? If you navigate to the "root" folder of your game and right-click on the SH4.exe program, and then left-click to choose "Properties", on that first "General" tab, toward the bottom under "Attributes", is the "Read-only" box checked? Are you therefore certain that you have LAA set correctly on the SH4.exe file?
If all of that looks fine, did you by chance happen to try to Save with a Replay at any point on this patrol? Navigate into your Save folder (generally C:\Users \UserName \Documents \SH4, unless you've changed it), go into "data", "cfg", "SaveGames", and find the latest date / time stamped and numbered folder there (hex numbers, so you will possibly see the letters A-F). If you select it in Windows 7, the Status Bar gutter across the bottom will have the info, but with Windows 10, you usally have to right-click the folder name, and choose "Properties" - you want to see what the size of the Save is, like "357kb" (rather tiny) or "1.48mb" (smaller than average), or "2gb" (whoops!) - fictionalized numbers, of course...
