On the comic "Forty Milleniums of Cultivation", the site does not update Progress any further than 13/15, despite multiple attempts at cycling through the chapters.
Site is not updating comic Progress properly
I have the same issue, Also Cultivation Chat Group comic has a similar problem.
"Cultivating the Divine" doesn't update progress beyond 0/11
Idem
It also happens to me with "Cultivation Chat Group" the progress is stuck in 15/17
Hasn't updated the progress for the latest 2 chapters released for Battle Frenzy and latest chapter of Versatile Mage. Seems like its a recent bug that has popped up possibly 1-2 weeks ago.
I have been reading Cultivation Chat Group and the progress would not go higher than 15/17. I have tried it on both desktop, mobile, and app to no avail.