My titles are disappearing

I’ve noticed over the past week or so that my titles on a number of sites are just disappearing. I am left with the page URL. The <title></title> field is blank.

In each case I am using Woo Canvas as my theme.

However it seems random. In some cases my titles are there and in other cases they are not. If I add my site name into the Settings – General my titles come back however this shows through my logo.

If I choose “Force rewrite titles” then in most cases my titles come back but in some cases they still do not.

Does anyone have any ideas? I am totally flummoxed. Latest version.

https://www.ads-software.com/plugins/wordpress-seo/