Steinberg have just sent out an official statement regarding difficulties with the Steinberg Installer for all current products on Apple's Yosemite (OS X 10.10).
Apparently there is an incompatibility between the current Steinberg Installers and the Apple OS - due for release in the Autumn.
"In light of the forthcoming operating system OS X Yosemite recently announced by Apple we have unfortunately identified an issue with our software."
They go on to say:
"The issue is owing to our current installer as implemented through the entire range of our software products. If you are planning to update to Yosemite this fall or to take part in the Yosemite beta-testing program, please be aware that our software products as are cannot be installed on this operating system. Current Steinberg software installed before updating to OS X Yosemite is not affected.
"The solution we offer is a small software tool currently available as downloadable pre-release version from our website which will enable a seamless installation of our existing software range on the OS X Yosemite operating system."
Unfortunately, there is no link provided, so probably best to contact Steinberg support for it.
"Again, we recognize this issue may cause some confusion. I want to emphasize that the issue has duly been addressed and you can continue to use our software products with confidence on the upcoming operating system announced by Apple."
Good to know they are aware of it and are prepared to go public and acknowledge the fact.