As you know I'm not shy about blaming Avid for things, but in this case many other interfaces can handle sample rate changes with Pro Tools without all these issues. Pro Tools is the default market leader. Focusrite should be just fixing their side to make it work, and testing with Pro Tools during development should always have happened. Is there documentation on their site explaining to their customers how to deal with their interfaces with this know issue with that market leading software? I am suspecting you may have a too rosey view of how Focusrite are treating you.
(Not looked into these in detail but a quick Google search makes it look like possible issues with different Focusrite interfaces and not all Pro Tools related).
... a different Scarlett interface when the DAW sample rate change does not work...
https://support.focusrite.com/hc/en-...lett-interface
... A few Focusrite uses having sample rate setting problems with an S1...
http://forumsarchive.presonus.com/posts/list/14630.page
etc.
Focusrite not having their own support forum is another hit against them.