I think I may have inadvertently resolved this issue by simply uninstalling the game, deleting the Factorio folder in the Roaming folder, then reinstalling it again. For good measure, I used the Mods UI in the game's main page to download instead of from a browser & cut+paste. Had to start a new ...

I was told in the unofficial Discord to seek assistance in the forums, so here goes. I've been experiencing a strange bug of sorts since I purchased the Space Age DLC. Prior to that, I never experienced this issue or any bugs whatsoever.

When I start a new game, it runs fine for about half an hour ...