Your users might have installed a JavaScript blocking browser plugin/extension that uses the EasyList or similar list. This is especially likely if the number of users missing from Intercom is only a small and infrequently occurring percentage.
Why would an adblocking extension or plugin block Creabl?
While Creabl isn't an ad-provider, adblocking plugins (e.g. uBlock, Ghostery, Adblock, NoScript, and Firefox Privacy Browsing mode) offer options to block JavaScript that includes tracking functionality.
Since Creabl communicates conversation detail as well as offering the ability to submit attributes and events on your Users' behavior, we are included in some of these secondary lists. Though there are many lists, the majority of Creabl blockages are caused by our inclusion in the EasyList list.
At Creabl, we respect customer privacy where requested so we don't argue against our inclusion here, but you can certainly request that your users disable plugins like this, or add an exception for your site for better performance.
How can I keep data in Creabl synced with my system for these users?
You can ask your users to disable JavaScript blockers. Googling for JavaScript blocker detection or Adblock detection will provide many resources on doing this.
If you believe you're missing user detail in Creabl for other reasons, feel free to get in touch to look into potential integration issues.