After reading a comment from Dan over at No Facilities, I have been doing a little experimenting.
I have been unable to comment on blogs that were paid or self hosted. Dan has been chasing this issue with the Happiness Engineers for a while now. WordPress has a feature that allows us to verify our credentials across platforms so we can comment without filling in all that information for every comment we post.
I use all Apple products. A feature was added to my Safari browser (not sure when) called ‘prevent cross-site tracking’ which is intended to protect your privacy and prevent other websites from tracking which websites you frequent for the purposes of targeted advertising. I believe this may also prevent WordPress from carrying your credentialing forward to external sites such as other WordPress blogs.
I switched off the tracking and so far I can comment freely with no difficulty. In Chrome, a similar feature exists called ‘Allow cross-website tracking’. Firefox has a similar feature although from what I read, they do not block login-credentials, so I will test there, too.
If this Is indeed the culprit, I will most likely start using two different browsers – one for blogging and one for everything else where I can prevent the cross-site tracking. And please, do not fool yourself. I have had this feature on and websites still track me. I guess a feature is only effective if everyone adheres to it.