Galaxy and GOG are not working together. I had an update (to give one example) for Age of Decadence showing in GOG. I open Galaxy and wait a couple of minutes, but no auto update. So I do a verify and this updates the game. I have had to do this with 6 other games that still show in "updates" in my GOG library even though they have been updated in Galaxy.

Seems Galaxy doesn't know what you do in GOG and vice versa!

The relevant blues are more likely to see a bug report if you post it to Mantis or https://www.gog.com/forum/general/gog_galaxy_beta_2

According to the changelog, the first check for updates used to be made after five minutes, but it's supposed to be made after 15 seconds since version 1.1.19.