Adding frame to Aseprite animation no longer auto-slices tiles properly

After updating from 6.0 to 6.2 I noticed that adding a new frame to an .aseprite file now completely breaks the sheet. Previously it would automatically re-slice the sheet and integrate the new frame for you just fine.

Original .aseprite file

Same .aseprite file after adding 2 new frames at the end of the animation

I also noticed this new dialog about feature deprecation…

I hope this change isn’t intentional, hopefully I have this wrong? This is a massive part of my workflow. Due to the incorrect slices I’m unable to use the animations generated from the Aseprite file, which was the entire point of using this system.

As I see it right now I’d have to manually recreate the animation clips in Unity. My current workaround is using new separate files instead of updating the original, though obviously this isn’t great.