I'm using the latest versions of WP, Yoast and Transposh. My problem occurred a few months ago and the Transposh author resolved it for me, by making changes in the Yoast SEO plugin. I believe (but am not 100% sure) the problem started again after the latest updates.
I know it is a conflict because the Transposh translation plugin works when I deactivate Yoast SEO.
The problem is a redirect loop error. http://wordpress.org/support/topic/bug-with-clean-permalinks-running-anyhow?replies=3
I am the author of Transposh, and users have been complaining about pages that kept redirection loops.
I have discovered this to come from the fact that the clean permalinks function of Yoast was working even if it appeared unticked in the settings page.
Actually, the object had the "on" property for the settings looking at a stack trace.
This can be easily traced creating an on_wp_redirect trigger and making a trace.
If you need further info, I'll be happy to provide it.
Current solution - had to comment out the clean permalinks triggers you have added in the frontend-object file.
And, the latest reply to me through email.
I guess there is a file there called frontend-object (probably .php), and I guess there are triggers by clean permalink there
The SEO plugin has a bug, there's nothing I can do on my side to fix that (at least that I am aware of), they ignore their own setting and ignored the bug report I posted on their forum,
there is little I can do.
I can suggest you talk to them, ask them to clean up things a bit, or patch the file manually every time.
You can also drop transposh, (or them) but I hope you won't come to that
Please let me know if you can make these plugins compatible.