I have installed Lightroom 5.7 to be able to continue working but need to have LR6 up running...
All other programs run fine, so I believe this is an LR issue. I have read about similar issues with LR CC, but cannot find anything about LR6.
Did you download and install? You can’t use a data transfer tool or copy a Time Machine backup of an application.
If so trash the LR6 installation and download and install LR6.0 from the link below. After successful installation download the LR6.5.1 update.
When I first had the problem after restore, I uninstalled LR6 before downloading and install. But same result every time.
I have done recover from Time Machine before and have never had this problems with LR or any other applications.