Thanks for the mention, John.
To the OP -
What I've found through personal experience, testing for our company, and listening on this forum is that there are two main reasons HDMI switchers fail to work:
1) Improper implementation of HDCP on the source or display device, or
2) Improper implementation of HDCP on the switcher itself
The first problem isn't the switcher's fault. It's the fault of the HDMI devices connected through it. Many early cable boxes, for example, didn't recognize "repeater" devices, which is what a switcher is considered in the HDCP world. Therefore, when connected directly to a display, the source worked fine, but when run through a switcher, it didn't work because that unit's HDCP programming throught the switcher was some sort of illegal black box, and therefore wouldn't work.
The second problem can be easily remedied or prevented by the manufacturer building an HDCP compliant product, then putting the switcher through both HDMI and HDCP compliance testing. Many low cost switches (and even some high-cost ones, surprisingly) aren't compliance tested because it's expensive and would raise their cost. It also means that problems are sometimes common with those switchers (this varies from brand to brand, build to build). You see, HDMI compliance testing is required currently for HDMI products, but HDCP compliance testing isn't required.
So it's important to buy an HDMI and HDCP compliance tested switcher so you can have reasonable confidence that it will work both now and in the future.
That's my informational blurb for the day
Trent