There was significant change in core during 2-3 days ago, so don't sync with git until you check your theme. Maybe older php version are safe, I don't have time to dig in core to find it. That change is improvement...
THEME_LAYOUT value (to detect the actual layout) is not available anymore outside theme and theme_shortcodes classes. It is probably that themes without those classes work legacy way.
It can be fixed, but it is time-consuming, so wait with sync until you know what to do. I will release new versions only after the official release. With so many themes - the priority depends on actual users contact me (to know that theme is used), the premium themes first.
As you can see, actually this theme is broken too. So you have troubles if:
- your theme uses JMTheme plugin for working with layouts
- your theme uses THEME_LAYOUT constant. So just check this.
The code inside head tags
Custom theme shortcodes