This is exactly the problem. The content for 1.14.5.0 should not have downloaded in-game unless the correct 1.14.5.0 executable (from the Store) was in place first. All the content that follows depends on the right executable being installed first.
In previous sim updates, launching the sim would immediately send you to the store to get the new executable (typically about 1 GB in size). If for any reason the store update was not installed, subsequent launches of the sim would send you right back to the store. It would not proceed any farther until the store update was first installed.
This time, (apparently), the sim skipped the “store check”, and went right ahead and started installing 1.14.5.0 content with the old 1.13.7.0 executable still in place, which led to many of the reported issues - “fly now” button greyed out, inability to select airports on the world map etc.
I didn’t have the issue. When the forums announce a new update has gone live, I always go directly to the store and insure the new update is downloaded and installed there before even trying to open the sim itself.
As for why you currently can’t get the store to install the new update, I can’t offer any advice. I have found the store updater is not very user friendly, and I often have to switch back and forth between “all” and “owned” content, and click on the “get updates” button several times before it will finally find, download and install the new Flight Simulator core file.