Hey folks. One of my players in my campaign is playing a bladesinger wizard, but when using the bonus action to activate it, nothing on the character sheets get updated (movement speed, AC, advantage on acrobatics, etc.). Am I doing it wrong or is this a bug?

Thanks!

Neither. It’s not currently part of DDBs feature set. Blade song, like rage and several other features and the effects of certain spells are ltemporary effects” that cannot currently be reflected automatically on the sheet. It is on the roadmap. At least some of the effects can be noted by making manual adjustments to the sheet. 

The method I use for temporary effects is to create homebrew items that you can equip/unequip as necessary. Best to make them Artifact quality items so they sort to the top of the equipment list and make them Wondrous Items rather than Armour or Weapons so they don't give other mechanical benefits than what you set.