Britain 1900 Large Fleets Manual legacy fleet Version 1.05
Bug occurred during end stages of a medium-sized battle in the late 1940s, 3 BCs and a bunch of cruisers and destroyers on each side, and aircraft all over the place. Have had similar before as well, but was in a game where I'd updated through 3 patches, so assumed it was related to that. There were errors both in the game, and after saving and exiting (screenshots of both attached).
After reloading the issues went away for a bit, and then the game stopped 'auto running' (needed a return pressed after ever turn to keep moving), and gave out of memory error when trying to save. Screens attached, but game didn't save (those Bremen class BCs got lucky!) so couldn't attach anything new here.