Apparently Russia bolstered their forces to 25K soldiers in that area. They are now at risk of being cut off from supply as the bridges to their area are being destroyed. Was it all a feint? That would imply a level of ingenuity the Ukrainian Army hasn’t displayed anywhere else.
If a party in a war says it will definitely, positively do X, you can bet that X is the last thing on their mind. It’s called disinformation. Did the Allies say they would definitely invade Normandy?