Thanks for the response,
Problem Description: on a new/fresh reinstallation of Logic Pro (Not version X) from the App Store, the first thing it does on launch is attempt to download an "Essenitial Software" file of 2 GB in size. The only option is "Quit" which also quits logic if you select it. This also occurs for the GarageBand and MainStage Applications I reinstalled on my macs.
This download will progress all the way to the end, and then FAIL, reporting that the content could not be downloaded.
All menus from within Logic Pro are disabled so there is no way to perform an increment installation of this content.
All discussion threads on this topic that I could find had no solution. One pointed to a link that was dead. One mentioned interference from Little Snitch. I have it on one machine, but not others, and the behavior is the same for all of them.
I called into Apple support, and requested a support callback. While waiting for the callback, I decided to search the support downloads section on my own, on a lark specifically for Logic Pro 9 software, and found the updaters and installers for version 9 and prior. There are two files, a smaller one and a much larger one (over 18 GB). I downloaded and installed the smaller of the two, and was downloading the larger of the two when Apple Support returned my earlier call. The support person confirmed that I had stumbled upon the correct course of action to resolve this issue.
After ALL the content of the latter one was installed (there are many smaller images to install separately), I was able to get Logic operating properly again. Of course, it still tried to continue downloading the 2 GB file that will fail, and I cancelled it.
When I restarted the CPU after all of this, it reported that all content was installed.