I am guessing you are using the conditional tab to mark the overlay group upon hover “This element is visible : yes”. Do you mean you need to connect a hover action to a workflow so that you can animate it instead? ie: Element Actions → Animate?
My first instinct would be to set a custom state upon hover and allow that custom state to control a “Do when condition is true” workflow with animation, but unfortunately this does not exist in Bubble from what I can tell. You may be able to the use the Toolbox plugin and achieve this effect with JavaScript that triggers a workflow (actually now that I think about it this is completely doable) — check it out: Toolbox plugin - collection of utility elements
If I find the time I’ll post back with an example using the plugin.