Custom Link Posts are Having Links Shortened When Beginning with 'https'

Hi,
I have a very curious problem with a live site that needs to be resolved ASAP. On the site a client is using the Link ‘post format’ all over the site, so she is putting the link in the content and then choosing the Link post format.

This seemed to work fine in the past but recently we noticed that some of the links aren’t showing correctly, only the first 60 characters are, which makes the links unusable.

To add even more intrigue is the fact that I’ve realised that this is only happening with links that begin ‘https’ and not ‘http’ links, hence why we never noticed this problem before.

I’ve tried looking into this and can’t quite work out where this error is occurring. How can we fix this? As right now the site just has SO many broken links.

Best,
Russ