This is a very nuanced problem and most people will likely not care that instead of getting a nice preview icon on your PDF’s you get the traditional Adobe general PDF icon. If you are the type of person who wants your computer to work the way you have set it to work and do not accept “its a bug” as a viable alternative, I found this site that actually provides the fix that Adobe hasn’t included despite the author of this fix providing it directly to them. This is a bug in Adobe’s PDF software related to Windows on 64-bit hardware. The fix can be found here and involves tweaking the Windows registry to resolve the issue on behalf of Adobe. If you would like to see this fix in Adobe’s software please provide that feedback here. Thankfully, the author has provided a very convenient GUI that evaluates your system, determines if the fix is needed and provides a single button to fix the “bug”.