I don't see how a link could appear and disappear unless actually removed. When I told the other camgirl that I couldn't see her twitter link, she checked her profile and at the same time that I couldn't see it, she could.
Here is all the Twitter link section from the help centre for info:
Can I put a link to my Twitter page in my Profile and/or Links Section?
Due to the abuse of linking to Twitter, as expected, we will now only accept links to Twitter in the Links section of your Profile. (Edit Profile Page -> Manage Links button.) Please do not put your Twitter username anywhere in your profile details or summary, or email signatures or auto responses.
Your Twitter page/account must also meet these two requirements:
You must be following @Adultworkcom
Your Twitter profile must include a link to your AdultWork.com Profile Page.
We may remove Twitter links if we believe that they are being used to negate or abuse any functionality provided by the Site.
E.G. Please do not put "For my phone number" or "To see my availability" as the link text.
The Link URL should simply be:
https://twitter.com/your_twitter_username
You do not need to include the @ sign.
We believe it reasonable to ask that if you want existing AdultWork.com visitors to jump to another site, that you reciprocate by referencing your AdultWork.com profile on that site. This of course is true of traditional profile links too, where the display of banner is requried.
A benefit of following @Adultworkcom is that you will see updates about new Site functionality and the status of any downtime or outage.