During the last week or so Simple Captcha started to always fail, preventing users from registering. The only workaround we found was to disable the CAPTCHA altogether, which leaves the registration open for unwanted spam users.
This affects both 1.2.9a and 1.2.91 versions of the plugin. The only possible cause I can think of is another plugin update that has caused this conflict. Or it could be WordPress core 3.5, but in that case I'd expect more sites to be affected. Perhaps something with Events Manager 5.3.3 (which also affects 5.3.5)? Quote from the changelog for 5.3.3:
- fixed loading of unused post meta overwriting post fields/properties
- removed usage of PHP sessions in exchange for temporary cookies
- fixed conflict with caching plugins and booking forms due to cached wpnonces
Any pointers on how to find out what part of what plugin might be messing with this?