If an article's title has an ampersand in it, it will ignore the "action=render" parameters on the URL.
Here's an example:
http://tmbw.net/wiki/Installing_%26_Servicing_Melody/Release_Details?action=render
And here's an example of it working properly on an article that doesn't have an ampersand:
http://tmbw.net/wiki/Installing_And_Servicing_Melody/Release_Details?action=render
Version: 1.15.x
Severity: minor
URL: http://tmbw.net/wiki/Installing_%26_Servicing_Melody/Release_Details?action=render