Re: Buttons and other UI elements not showing
You need to revise HTML structure in BP templates transferred to your active theme in Step Three of the compatibility process. Plus copy some styling from bp-default’s style.css and adjust to taste.
BP Template Pack Process – https://codex.buddypress.org/theme-development/wordpress-to-buddypress-theme/
Template Pack Walkthrough – https://codex.buddypress.org/theme-development/bp-template-pack-walkthrough-level-easy-2/