There was news ~week ago that a 2000 soldier column of naval infantry was advancing towards Odessa? Never heard anything of them…Ukrainian forces withdrew into the city, set up positions in civilian areas, and prevented civilians from escaping. They've been cut off from the rest of the country. There's been no significant counterattack from them for several days now.
I think Russia plans on keeping Odessa so will be happy to just put it under siege and pick away at the enemy until they surrender rather than to go in and destroy the city.