I'm using symlink to point my LR preferences from default "~/Library/Application Support/Adobe/Lightroom" to another location.   LRT5 installed presets to that default location causing my symlink to be overwritten and I had to relink plus manually migrate whatever LRT5 copied therein over.  Not sure whether this caused another issue which is the unable to export error that I will report on another thread.  Anyway I don't recall this happening when I was using LRT4.  Currently using Lightroom Classic CC v7.1 on Mac OS X 10.13.3.  Thanks!

I see. Will try to fix the installer in 5.0.2 to follow symlinks when installing the addons.

Fixed in 5.0.2: https://lrtimelapse.com/news/lrtimelapse-5-0-2/