I tried to override sobject "New" Button with below code, it's working in salesforce lightning experience. the same sobject i am using in Community navigation menu item.
<aura:component Implements="flexipage:availableForAllPageTypes,forceCommunity:availableForAllPageTypes,lightning:actionOverride" access="global" > <div>custom overridden Lightning component</div> </aura:component>
but in community after click the sobject menu item lists shows and all other standards buttons are visible in list view top right corner except overridden "New" button. i found this link after i search in forum.
is there any ways to get those overridden components in to community.