As I said in the bug forum, I had the same problem with thousands of five second turns in a row. I resolved it by killing the .exe three times - I mean I had three "increment placeholders" in a row in the events window eventually.
Keep killing even if 5 second turns resume after a few longer turns (even 30 day turns). It became unstuck soon after.
Of course I don't have the code, and it might be coincidence But to have that many 5 sec "combat" turns for seven hours real time, and then getting out of it by interrupting a process? It seems non-intended, not NPR combat related. Maybe somebody can try this and confirm or not.