The reminder option is missing for me as well. It is missing in the script that is getting enqueued to the front end:
var $buoop = {required:{'.$browser.'},test:'.(isset($wpbu_js[1]) ? $wpbu_js[1] : '').',newwindow:'.(isset($wpbu_js[2]) ? $wpbu_js[2] : '').',style:"'.(isset($wpbu_js[3]) ? $wpbu_js[3] : '').'",insecure:'.(isset($wpbu_js[4]) ? $wpbu_js[4] : '').',unsupported:'.(isset($wpbu_js[5]) ? $wpbu_js[5] : '').',mobile:'.(isset($wpbu_js[6]) ? $wpbu_js[6] : '').',shift_page_down:'.(isset($wpbu_js[7]) ? $wpbu_js[7] : '').',api:2021.01};
If I understand the plugin and browserupdate.org correctly, the reminder option should be appended to this options object.
