Hmm, so in Advanced Interface Options, the buff durations show as 1 (meaning ON). So the /console command probably won’t have any effect on it either.
/console buffDurations 1
/console buffDurations 0
Only other thing I can recommend would be a full UI reset (as detailed in Support article linked below) to rule out a misbehaving addon or corrupted UI.
Please note, this is not the same as disabling addons OR doing a /reload of your UI.