Ad/Tracking Blockers
Your browser might have a JavaScript blocking browser plugin/extension that uses the EasyList or similar list.
While Intercom isn't an ad-provider, ad-blocking plugins (e.g. uBlock, Ghostery, Adblock, Adblock Plus, NoScript, and Firefox Privacy Browsing mode) offer options to block JavaScript that includes tracking functionality.
Since Intercom communicates conversation detail as well as offering the ability to submit attributes and events on your behavior, Intercom is included in some of these secondary lists. Though there are many lists, the majority of Intercom blockages are caused by its inclusion in the EasyList list.
How to check your extensions
Chrome: go to chrome://extensions/
Firefox: go to about:addons and click the Extensions tab
Safari: Click Safari in the top bar, then Preferences , then click the Extensions tab
Edge: Click the menu button at the top right, then click on Extensions
Web Browser Tracking Protection
Using Firefox privacy mode can block the Chat button
If you're using the browser Firefox and starting a private browsing session, by default it will block the Chat button. You can enable the button again by changing the setting on the first page that opens in private mode as shown bellow:
