In current version of Android Studio Arctic Fox (2020.3.1 Canary 12) I always have toolbar button Apply Changes and Restart Activity in disabled state.
Mouseover hint says: Apply Changes and Restart Activity (disabled: debug execution)
Hint in status bar says: Apply changes and restart activity is disabled for this device because it is currently not allowed during debugging
None of these messages help me in understanding of why "it is currently not allowed". With this feature not available it is not possible to apply hot-updates to activity layouts.
Note: similar button "Apply Code Changes" works OK.
Any ideas how to enable "Apply Changes and Restart Activity"?