When uploading and importing a list of subscribers into beehiiv, there are several reserved fields (listed below) that are not able to be imported as custom fields.
"rp_num_referrals"
"rp_num_referrals_until_next_milestone"
"rp_display_with_milestone_styles"
"rp_display_with_no_milestone_styles"
"rp_next_milestone_name"
"rp_personalized_text"
"rp_next_milestone_image_styles"
"rp_next_milestone_image_url"
"rp_referral_hub_url"
"rp_refer_url"
"rp_referral_code"
"app_version"
"browser"
"city"
"country"
"device_type"
"landing_page
"latitude"
"longitude"
"os"
"os_version"
"platform"
"referrer"
"referring_domain
"region"
"user_agent"
"utm_campaign"
"utm_content"
"utm_medium"
"utm_source"
"utm_term"
"email"
"OPEN_TRACKING_PIXEL"
"reward_promo_code"
"subscriber_email_hash
"subscriber_id"
"subscriber_refer_url"
"subscriber_referral_hub_url"