got this bug.. extremely annoying.
it comes in 2 different kind: when you select the full party, they run like in fast mode even though it's in normal mode, or they run like in stealth mode even though stealth isn't activated
the bug happens only when more than one character is selected
sometimes, activating stealth and deactivating it removes the bug, but doesn't work all the time
for the faster speed, it seems to only happens after loading a save. Moving a single character then selecting your full party seems to remove the bug