U9 to V12 Data Migration - Folder Validation in V12 runs "Dictionary Update Utilities" and deletes data types, screens, etc.

I think you need to assign activity codes to protect modifications from deletion.  I know i forgot to do this on a field once and lost it during the process. 

I tried to find an explanation but didn't find much.

Activity codes that are customizations or for verticals start with X, Y, or Z, indicating they are considered non-standard and are not affected by patching.   Activity codes starting with  X is for vertical add ins, Y is for business partner or Sage PSG group changes and Z is for customer changes.

Found this... from a presentation I think at the Sage X3 meeting in 2020.  It was called Managing Customizations.   Not mine to distribute but maybe someone at Sage has it. 

• Protect and Identify your customizations
• Keep updates and patches from overwriting your changes
• Search utility to find customizations
• Also used to disable customizations or for array sizing
• Naming conventions to follow
• Names can be up to 5 characters
• Must begin with X, Y or Z
• X – Add-ons (Sage R&D, Partner or ISV created – when assigned by Sage)
• Y – Partner created customizations
• Z – Customer created customizations

Thanks for this info Stephen, unfortunately in my case, the data types, etc. which are being deleted during folder validation, are indeed protected with activity codes.

Sounds a bit of a strange issue, so would suggest you raise this with Sage Support for more detailed review