Macmini won't update past 13.4

Machine: Macmini6.2
OCLP version: 0.6.8
macOS: Installed 13.4
Issue: Have not been able to update past that version.
Notes: Standard install - no mods to settings.
Won't allow download of installer from Mac App Store - opens System Settings and complains . Successfully used on Macbookpro11,4 & MacBookAir6,1 - both updated to 13.6 without issue.

Sys Info

OCLP Info

App store error