We have two different environment(server) for WordPress. One of them is having no issues with the More tag. I added <!--more--> within the post and I see the more link in the post page.
Same thing dosent work in other env that we have. Tried two ways...
1) Add more manually by pasting <!--more--> within the post
2) In Visual tab, added more tag using "Insert More tag" button.
Both the ways, once I click on "Update" and save the post, its getting converted to <!--more-->
This happens only for < and >.