Apparently, some changes introduced in 5.13 cause problems wile starting on the 5.12 base. Tested on Windows, 5.13 has been uninstalled with the Installer and then 5.12.1 and 5.13.0 were installed again from the production account. When Neptune3 5.12.1 starts, the cluster and the HUD are empty and the center console window shows widgets complaining that apps are not running. Apps are listed in the launcher but their icons are not show.

Initially, new QSettings values for auto-recovery were suspected as a root cause. After some more testing it looks like it is the app database in in appman. Starting Neptune with -r fixes the problem.