The license key is active for the site. I even de-activated it and re-activated it and I am still not getting any prompt to update the plug in. On the custom fields > updates page, the license is active and it says an update is available. When I click it though, it takes me to the plug in page and there is no option to update.
I am having the same issue. I have version 184.108.40.206 installed. When I go to the custom fields > updates page, it says there is an update to 5.4.10 but the option to update the plugin never shows up on the plugins page. So I can not update ACF.