WHMCS has released V7.2.3 – on July 18, 2017 – which includes the CORE-11346 fix. The hotfix detailed below is no longer necessary.
The team at WHMCS has released version 7.2.2 to the public, available for download as of last week.
We have notified WHMCS of an issue we identified with the getclientdetails API after upgrading to V7.2.2 that will break our module in most cases (pushing invoices, creating orders, etc).
In response to our report, WHMCS has rectified the issue and posted a blog post with an included hotfix to patch this issue until WHMCS V7.2.3 is released. You can find this post here
In light of this report / hotfix, we will not be issuing a module update, as the issue lies with WHMCS V7.2.2, and not our module. Once this hotfix is applied, the module will function as designed!