I'm surprised you managed to get version 1.4.0 working for tsoHost. I fixed an issue affecting tsoHost customers in version 1.4.1. Unfortunately that issue isn't related to what you're seeing.
I see two production certificates issued today for claysnow.co.uk:
The current certificate being served for claysnow.co.uk is actually for a different domain name:
I'm not currently sure why UAPI won't install your cert. I need to look into this further when I have more time. For now though, you should be able to use the legacy, manual instructions to install your certificate for claysnow.co.uk into cPanel: